SQLAlchemy 2.0 Documentation

ORM Execution Options - documentation on all ORM-specific execution options

method sqlalchemy.sql.expression.CompoundSelect.exists() → Exists¶

inherited from the SelectBase.exists() method of SelectBase

Return an Exists representation of this selectable, which can be used as a column expression.

The returned object is an instance of Exists.

See also

EXISTS subqueries - in the 2.0 style tutorial.

New in version 1.4.

attribute sqlalchemy.sql.expression.CompoundSelect.exported_columns¶

inherited from the SelectBase.exported_columns attribute of SelectBase

A ColumnCollection that represents the “exported” columns of this Selectable, not including TextClause constructs.

The “exported” columns for a SelectBase object are synonymous with the SelectBase.selected_columns collection.

New in version 1.4.

See also

method sqlalchemy.sql.expression.CompoundSelect.fetch(count: _LimitOffsetType, with_ties: bool = False, percent: bool = False) → Self¶

inherited from the GenerativeSelect.fetch() method of GenerativeSelect

Return a new selectable with the given FETCH FIRST criterion applied.

This is a numeric value which usually renders as FETCH {FIRST | NEXT} [ count ] {ROW | ROWS} {ONLY | WITH TIES} expression in the resulting select. This functionality is is currently implemented for Oracle, PostgreSQL, MSSQL.

Use GenerativeSelect.offset() to specify the offset.

Note

The GenerativeSelect.fetch() method will replace any clause applied with GenerativeSelect.limit().

New in version 1.4.

Parameters:

count – an integer COUNT parameter, or a SQL expression that provides an integer result. When percent=True this will represent the percentage of rows to return, not the absolute value. Pass None to reset it.
with_ties – When True, the WITH TIES option is used to return any additional rows that tie for the last place in the result set according to the ORDER BY clause. The ORDER BY may be mandatory in this case. Defaults to False
percent – When True, count represents the percentage of the total number of selected rows to return. Defaults to False

See also

method sqlalchemy.sql.expression.CompoundSelect.get_execution_options() → _ExecuteOptions¶: inherited from the Executable.get_execution_options() method of Executable

Get the non-SQL options which will take effect during execution.

New in version 1.3.

See also

Executable.execution_options()

method sqlalchemy.sql.expression.CompoundSelect.get_label_style() → SelectLabelStyle¶: inherited from the GenerativeSelect.get_label_style() method of GenerativeSelect

Retrieve the current label style.

New in version 1.4.

method sqlalchemy.sql.expression.CompoundSelect.group_by(_GenerativeSelect__first: Literal[None, _NoArg.NO_ARG] | _ColumnExpressionOrStrLabelArgument[Any] = _NoArg.NO_ARG, *clauses: _ColumnExpressionOrStrLabelArgument[Any]) → Self¶

inherited from the GenerativeSelect.group_by() method of GenerativeSelect

Return a new selectable with the given list of GROUP BY criterion applied.

All existing GROUP BY settings can be suppressed by passing None.

e.g.:

stmt = select(table.c.name, func.max(table.c.stat)).\
group_by(table.c.name)

Parameters:: *clauses – a series of ColumnElement constructs which will be used to generate an GROUP BY clause.

Ordering or Grouping by a Label - in the SQLAlchemy Unified Tutorial

method sqlalchemy.sql.expression.CompoundSelect.is_derived_from(fromclause: FromClause | None) → bool¶

Return True if this ReturnsRows is ‘derived’ from the given FromClause.

An example would be an Alias of a Table is derived from that Table.

method sqlalchemy.sql.expression.CompoundSelect.label(name: str | None) → Label[Any]¶: inherited from the SelectBase.label() method of SelectBase

Return a ‘scalar’ representation of this selectable, embedded as a subquery with a label.

See also

SelectBase.scalar_subquery().

method sqlalchemy.sql.expression.CompoundSelect.lateral(name: str | None = None) → LateralFromClause¶

inherited from the SelectBase.lateral() method of SelectBase

Return a LATERAL alias of this Selectable.

The return value is the Lateral construct also provided by the top-level lateral() function.

See also

LATERAL correlation - overview of usage.

method sqlalchemy.sql.expression.CompoundSelect.limit(limit: _LimitOffsetType) → Self¶

inherited from the GenerativeSelect.limit() method of GenerativeSelect

Return a new selectable with the given LIMIT criterion applied.

This is a numerical value which usually renders as a LIMIT expression in the resulting select. Backends that don’t support LIMIT will attempt to provide similar functionality.

Note

The GenerativeSelect.limit() method will replace any clause applied with GenerativeSelect.fetch().

Parameters:: limit – an integer LIMIT parameter, or a SQL expression that provides an integer result. Pass None to reset it.

See also

method sqlalchemy.sql.expression.CompoundSelect.offset(offset: _LimitOffsetType) → Self¶

inherited from the GenerativeSelect.offset() method of GenerativeSelect

Return a new selectable with the given OFFSET criterion applied.

This is a numeric value which usually renders as an OFFSET expression in the resulting select. Backends that don’t support OFFSET will attempt to provide similar functionality.

Parameters:: offset – an integer OFFSET parameter, or a SQL expression that provides an integer result. Pass None to reset it.

See also

Select.selected_columns

method sqlalchemy.sql.expression.CompoundSelect.options(*options: ExecutableOption) → Self¶

inherited from the Executable.options() method of Executable

Apply options to this statement.

In the general sense, options are any kind of Python object that can be interpreted by the SQL compiler for the statement. These options can be consumed by specific dialects or specific kinds of compilers.

The most commonly known kind of option are the ORM level options that apply “eager load” and other loading behaviors to an ORM query. However, options can theoretically be used for many other purposes.

For background on specific kinds of options for specific kinds of statements, refer to the documentation for those option objects.

Changed in version 1.4: - added Executable.options() to Core statement objects towards the goal of allowing unified Core / ORM querying capabilities.

See also

Column Loading Options - refers to options specific to the usage of ORM queries

Relationship Loading with Loader Options - refers to options specific to the usage of ORM queries

method sqlalchemy.sql.expression.CompoundSelect.order_by(_GenerativeSelect__first: Literal[None, _NoArg.NO_ARG] | _ColumnExpressionOrStrLabelArgument[Any] = _NoArg.NO_ARG, *clauses: _ColumnExpressionOrStrLabelArgument[Any]) → Self¶

inherited from the GenerativeSelect.order_by() method of GenerativeSelect

Return a new selectable with the given list of ORDER BY criteria applied.

e.g.:

stmt = select(table).order_by(table.c.id, table.c.name)

Calling this method multiple times is equivalent to calling it once with all the clauses concatenated. All existing ORDER BY criteria may be cancelled by passing None by itself. New ORDER BY criteria may then be added by invoking Query.order_by() again, e.g.:

# will erase all ORDER BY and ORDER BY new_col alone
stmt = stmt.order_by(None).order_by(new_col)

Parameters:: *clauses – a series of ColumnElement constructs which will be used to generate an ORDER BY clause.

Ordering or Grouping by a Label - in the SQLAlchemy Unified Tutorial

method sqlalchemy.sql.expression.CompoundSelect.replace_selectable(old: FromClause, alias: Alias) → Self¶: inherited from the Selectable.replace_selectable() method of Selectable

Replace all occurrences of FromClause ‘old’ with the given Alias object, returning a copy of this FromClause.

Deprecated since version 1.4: The Selectable.replace_selectable() method is deprecated, and will be removed in a future release. Similar functionality is available via the sqlalchemy.sql.visitors module.

method sqlalchemy.sql.expression.CompoundSelect.scalar_subquery() → ScalarSelect[Any]¶

inherited from the SelectBase.scalar_subquery() method of SelectBase

Return a ‘scalar’ representation of this selectable, which can be used as a column expression.

The returned object is an instance of ScalarSelect.

Typically, a select statement which has only one column in its columns clause is eligible to be used as a scalar expression. The scalar subquery can then be used in the WHERE clause or columns clause of an enclosing SELECT.

Note that the scalar subquery differentiates from the FROM-level subquery that can be produced using the SelectBase.subquery() method.

See also

Scalar and Correlated Subqueries - in the 2.0 tutorial

method sqlalchemy.sql.expression.CompoundSelect.select(*arg: Any, **kw: Any) → Select¶: inherited from the SelectBase.select() method of SelectBase

Deprecated since version 1.4: The SelectBase.select() method is deprecated and will be removed in a future release; this method implicitly creates a subquery that should be explicit. Please call SelectBase.subquery() first in order to create a subquery, which then can be selected.

attribute sqlalchemy.sql.expression.CompoundSelect.selected_columns¶

A ColumnCollection representing the columns that this SELECT statement or similar construct returns in its result set, not including TextClause constructs.

For a CompoundSelect, the CompoundSelect.selected_columns attribute returns the selected columns of the first SELECT statement contained within the series of statements within the set operation.

See also

New in version 1.4.

method sqlalchemy.sql.expression.CompoundSelect.self_group(against: OperatorType | None = None) → GroupedElement¶

Apply a ‘grouping’ to this ClauseElement.

This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by select() constructs when placed into the FROM clause of another select(). (Note that subqueries should be normally created using the Select.alias() method, as many platforms require nested SELECT statements to be named).

As expressions are composed together, the application of self_group() is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like x OR (y AND z) - AND takes precedence over OR.

The base self_group() method of ClauseElement just returns self.

method sqlalchemy.sql.expression.CompoundSelect.set_label_style(style: SelectLabelStyle) → CompoundSelect¶

Return a new selectable with the specified label style.

There are three “label styles” available, SelectLabelStyle.LABEL_STYLE_DISAMBIGUATE_ONLY, SelectLabelStyle.LABEL_STYLE_TABLENAME_PLUS_COL, and SelectLabelStyle.LABEL_STYLE_NONE. The default style is SelectLabelStyle.LABEL_STYLE_TABLENAME_PLUS_COL.

In modern SQLAlchemy, there is not generally a need to change the labeling style, as per-expression labels are more effectively used by making use of the ColumnElement.label() method. In past versions, LABEL_STYLE_TABLENAME_PLUS_COL was used to disambiguate same-named columns from different tables, aliases, or subqueries; the newer LABEL_STYLE_DISAMBIGUATE_ONLY now applies labels only to names that conflict with an existing name so that the impact of this labeling is minimal.

The rationale for disambiguation is mostly so that all column expressions are available from a given FromClause.c collection when a subquery is created.

New in version 1.4: - the GenerativeSelect.set_label_style() method replaces the previous combination of .apply_labels(), .with_labels() and use_labels=True methods and/or parameters.

See also

LABEL_STYLE_DISAMBIGUATE_ONLY

LABEL_STYLE_TABLENAME_PLUS_COL

LABEL_STYLE_NONE

LABEL_STYLE_DEFAULT

method sqlalchemy.sql.expression.CompoundSelect.slice(start: int, stop: int) → Self¶

inherited from the GenerativeSelect.slice() method of GenerativeSelect

Apply LIMIT / OFFSET to this statement based on a slice.

The start and stop indices behave like the argument to Python’s built-in range() function. This method provides an alternative to using LIMIT/OFFSET to get a slice of the query.

For example,

stmt = select(User).order_by(User).id.slice(1, 3)

renders as

SELECT users.id AS users_id,
       users.name AS users_name
FROM users ORDER BY users.id
LIMIT ? OFFSET ?
(2, 1)

Note

The GenerativeSelect.slice() method will replace any clause applied with GenerativeSelect.fetch().

New in version 1.4: Added the GenerativeSelect.slice() method generalized from the ORM.

See also

method sqlalchemy.sql.expression.CompoundSelect.subquery(name: str | None = None) → Subquery¶

inherited from the SelectBase.subquery() method of SelectBase

Return a subquery of this SelectBase.

A subquery is from a SQL perspective a parenthesized, named construct that can be placed in the FROM clause of another SELECT statement.

Given a SELECT statement such as:

stmt = select(table.c.id, table.c.name)

The above statement might look like:

SELECT table.id, table.name FROM table

The subquery form by itself renders the same way, however when embedded into the FROM clause of another SELECT statement, it becomes a named sub-element:

subq = stmt.subquery()
new_stmt = select(subq)

The above renders as:

SELECT anon_1.id, anon_1.name
FROM (SELECT table.id, table.name FROM table) AS anon_1

Historically, SelectBase.subquery() is equivalent to calling the FromClause.alias() method on a FROM object; however, as a SelectBase object is not directly FROM object, the SelectBase.subquery() method provides clearer semantics.

New in version 1.4.

method sqlalchemy.sql.expression.CompoundSelect.with_for_update(*, nowait: bool = False, read: bool = False, of: _ForUpdateOfArgument | None = None, skip_locked: bool = False, key_share: bool = False) → Self¶

inherited from the GenerativeSelect.with_for_update() method of GenerativeSelect

Specify a FOR UPDATE clause for this GenerativeSelect.

E.g.:

stmt = select(table).with_for_update(nowait=True)

On a database like PostgreSQL or Oracle, the above would render a statement like:

SELECT table.a, table.b FROM table FOR UPDATE NOWAIT

on other backends, the nowait option is ignored and instead would produce:

SELECT table.a, table.b FROM table FOR UPDATE

When called with no arguments, the statement will render with the suffix FOR UPDATE. Additional arguments can then be provided which allow for common database-specific variants.

Parameters:

nowait – boolean; will render FOR UPDATE NOWAIT on Oracle and PostgreSQL dialects.
read – boolean; will render LOCK IN SHARE MODE on MySQL, FOR SHARE on PostgreSQL. On PostgreSQL, when combined with nowait, will render FOR SHARE NOWAIT.
of – SQL expression or list of SQL expression elements, (typically Column objects or a compatible expression, for some backends may also be a table expression) which will render into a FOR UPDATE OF clause; supported by PostgreSQL, Oracle, some MySQL versions and possibly others. May render as a table or as a column depending on backend.
skip_locked – boolean, will render FOR UPDATE SKIP LOCKED on Oracle and PostgreSQL dialects or FOR SHARE SKIP LOCKED if read=True is also specified.
key_share – boolean, will render FOR NO KEY UPDATE, or if combined with read=True will render FOR KEY SHARE, on the PostgreSQL dialect.

class sqlalchemy.sql.expression.CTE¶

Represent a Common Table Expression.

The CTE object is obtained using the SelectBase.cte() method from any SELECT statement. A less often available syntax also allows use of the HasCTE.cte() method present on DML constructs such as Insert, Update and Delete. See the HasCTE.cte() method for usage details on CTEs.

See also

Subqueries and CTEs - in the 2.0 tutorial

HasCTE.cte() - examples of calling styles

Members

alias(), union(), union_all()

Class signature

class sqlalchemy.sql.expression.CTE (sqlalchemy.sql.roles.DMLTableRole, sqlalchemy.sql.roles.IsCTERole, sqlalchemy.sql.expression.Generative, sqlalchemy.sql.expression.HasPrefixes, sqlalchemy.sql.expression.HasSuffixes, sqlalchemy.sql.expression.AliasedReturnsRows)

method sqlalchemy.sql.expression.CTE.alias(name: str | None = None, flat: bool = False) → CTE¶

Return an Alias of this CTE.

This method is a CTE-specific specialization of the FromClause.alias() method.

See also

execution_options(), get_execution_options(), options()

method sqlalchemy.sql.expression.CTE.union(*other: _SelectStatementForCompoundArgument) → CTE¶

Return a new CTE with a SQL UNION of the original CTE against the given selectables provided as positional arguments.

Parameters:

*other –

one or more elements with which to create a UNION.

Changed in version 1.4.28: multiple elements are now accepted.

See also

HasCTE.cte() - examples of calling styles

method sqlalchemy.sql.expression.CTE.union_all(*other: _SelectStatementForCompoundArgument) → CTE¶

Return a new CTE with a SQL UNION ALL of the original CTE against the given selectables provided as positional arguments.

Parameters:

*other –

one or more elements with which to create a UNION.

Changed in version 1.4.28: multiple elements are now accepted.

See also

HasCTE.cte() - examples of calling styles

class sqlalchemy.sql.expression.Executable¶

Mark a ClauseElement as supporting execution.

Executable is a superclass for all “statement” types of objects, including select(), delete(), update(), insert(), text().

Members

Class signature

class sqlalchemy.sql.expression.Executable (sqlalchemy.sql.roles.StatementRole)

method sqlalchemy.sql.expression.Executable.execution_options(**kw: Any) → Self¶

Set non-SQL options for the statement which take effect during execution.

Execution options can be set at many scopes, including per-statement, per-connection, or per execution, using methods such as Connection.execution_options() and parameters which accept a dictionary of options such as Connection.execute.execution_options and Session.execute.execution_options.

The primary characteristic of an execution option, as opposed to other kinds of options such as ORM loader options, is that execution options never affect the compiled SQL of a query, only things that affect how the SQL statement itself is invoked or how results are fetched. That is, execution options are not part of what’s accommodated by SQL compilation nor are they considered part of the cached state of a statement.

The Executable.execution_options() method is generative, as is the case for the method as applied to the Engine and Query objects, which means when the method is called, a copy of the object is returned, which applies the given parameters to that new copy, but leaves the original unchanged:

statement = select(table.c.x, table.c.y)
new_statement = statement.execution_options(my_option=True)

An exception to this behavior is the Connection object, where the Connection.execution_options() method is explicitly not generative.

The kinds of options that may be passed to Executable.execution_options() and other related methods and parameter dictionaries include parameters that are explicitly consumed by SQLAlchemy Core or ORM, as well as arbitrary keyword arguments not defined by SQLAlchemy, which means the methods and/or parameter dictionaries may be used for user-defined parameters that interact with custom code, which may access the parameters using methods such as Executable.get_execution_options() and Connection.get_execution_options(), or within selected event hooks using a dedicated execution_options event parameter such as ConnectionEvents.before_execute.execution_options or ORMExecuteState.execution_options, e.g.:

from sqlalchemy import event

@event.listens_for(some_engine, "before_execute")
def _process_opt(conn, statement, multiparams, params, execution_options):
    "run a SQL function before invoking a statement"

    if execution_options.get("do_special_thing", False):
        conn.exec_driver_sql("run_special_function()")

Within the scope of options that are explicitly recognized by SQLAlchemy, most apply to specific classes of objects and not others. The most common execution options include:

Connection.execution_options.isolation_level - sets the isolation level for a connection or a class of connections via an Engine. This option is accepted only by Connection or Engine.
Connection.execution_options.stream_results - indicates results should be fetched using a server side cursor; this option is accepted by Connection, by the Connection.execute.execution_options parameter on Connection.execute(), and additionally by Executable.execution_options() on a SQL statement object, as well as by ORM constructs like Session.execute().
Connection.execution_options.compiled_cache - indicates a dictionary that will serve as the SQL compilation cache for a Connection or Engine, as well as for ORM methods like Session.execute(). Can be passed as None to disable caching for statements. This option is not accepted by Executable.execution_options() as it is inadvisable to carry along a compilation cache within a statement object.
Connection.execution_options.schema_translate_map - a mapping of schema names used by the Schema Translate Map feature, accepted by Connection, Engine, Executable, as well as by ORM constructs like Session.execute().

See also

ORM Execution Options - documentation on all ORM-specific execution options

method sqlalchemy.sql.expression.Executable.get_execution_options() → _ExecuteOptions¶: Get the non-SQL options which will take effect during execution.

New in version 1.3.

See also

Executable.execution_options()

method sqlalchemy.sql.expression.Executable.options(*options: ExecutableOption) → Self¶

Apply options to this statement.

In the general sense, options are any kind of Python object that can be interpreted by the SQL compiler for the statement. These options can be consumed by specific dialects or specific kinds of compilers.

The most commonly known kind of option are the ORM level options that apply “eager load” and other loading behaviors to an ORM query. However, options can theoretically be used for many other purposes.

For background on specific kinds of options for specific kinds of statements, refer to the documentation for those option objects.

Changed in version 1.4: - added Executable.options() to Core statement objects towards the goal of allowing unified Core / ORM querying capabilities.

See also

Column Loading Options - refers to options specific to the usage of ORM queries

Relationship Loading with Loader Options - refers to options specific to the usage of ORM queries

class sqlalchemy.sql.expression.Exists¶

Represent an EXISTS clause.

See exists() for a description of usage.

An EXISTS clause can also be constructed from a select() instance by calling SelectBase.exists().

Members

correlate(), correlate_except(), inherit_cache, select(), select_from(), where()

Class signature

class sqlalchemy.sql.expression.Exists (sqlalchemy.sql.expression.UnaryExpression)

method sqlalchemy.sql.expression.Exists.correlate(*fromclauses: Literal[None, False] | _FromClauseArgument) → Self¶: Apply correlation to the subquery noted by this Exists.

See also

ScalarSelect.correlate()

method sqlalchemy.sql.expression.Exists.correlate_except(*fromclauses: Literal[None, False] | _FromClauseArgument) → Self¶: Apply correlation to the subquery noted by this Exists.

See also

ScalarSelect.correlate_except()

attribute sqlalchemy.sql.expression.Exists.inherit_cache: bool | None = True¶

Indicate if this HasCacheKey instance should make use of the cache key generation scheme used by its immediate superclass.

The attribute defaults to None, which indicates that a construct has not yet taken into account whether or not its appropriate for it to participate in caching; this is functionally equivalent to setting the value to False, except that a warning is also emitted.

This flag can be set to True on a particular class, if the SQL that corresponds to the object does not change based on attributes which are local to this class, and not its superclass.

See also

Enabling Caching Support for Custom Constructs - General guideslines for setting the HasCacheKey.inherit_cache attribute for third-party or user defined SQL constructs.

method sqlalchemy.sql.expression.Exists.select() → Select¶

Return a SELECT of this Exists.

e.g.:

stmt = exists(some_table.c.id).where(some_table.c.id == 5).select()

This will produce a statement resembling:

SELECT EXISTS (SELECT id FROM some_table WHERE some_table = :param) AS anon_1

See also

select() - general purpose method which allows for arbitrary column lists.

method sqlalchemy.sql.expression.Exists.select_from(*froms: _FromClauseArgument) → Self¶: Return a new Exists construct, applying the given expression to the Select.select_from() method of the select statement contained.

Note

it is typically preferable to build a Select statement first, including the desired WHERE clause, then use the SelectBase.exists() method to produce an Exists object at once.

method sqlalchemy.sql.expression.Exists.where(*clause: _ColumnExpressionArgument[bool]) → Self¶: Return a new exists() construct with the given expression added to its WHERE clause, joined to the existing clause via AND, if any.

Note

it is typically preferable to build a Select statement first, including the desired WHERE clause, then use the SelectBase.exists() method to produce an Exists object at once.

class sqlalchemy.sql.expression.FromClause¶

Represent an element that can be used within the FROM clause of a SELECT statement.

The most common forms of FromClause are the Table and the select() constructs. Key features common to all FromClause objects include:

a c collection, which provides per-name access to a collection of ColumnElement objects.
a primary_key attribute, which is a collection of all those ColumnElement objects that indicate the primary_key flag.
Methods to generate various derivations of a “from” clause, including FromClause.alias(), FromClause.join(), FromClause.select().

Members

alias(), c, columns, description, entity_namespace, exported_columns, foreign_keys, is_derived_from(), join(), outerjoin(), primary_key, schema, select(), tablesample()

Class signature

class sqlalchemy.sql.expression.FromClause (sqlalchemy.sql.roles.AnonymizedFromClauseRole, sqlalchemy.sql.expression.Selectable)

method sqlalchemy.sql.expression.FromClause.alias(name: str | None = None, flat: bool = False) → NamedFromClause¶

Return an alias of this FromClause.

E.g.:

a2 = some_table.alias('a2')

The above code creates an Alias object which can be used as a FROM clause in any SELECT statement.

See also

attribute sqlalchemy.sql.expression.FromClause.c¶

A synonym for FromClause.columns

Returns:: a ColumnCollection

attribute sqlalchemy.sql.expression.FromClause.columns¶

A named-based collection of ColumnElement objects maintained by this FromClause.

The columns, or c collection, is the gateway to the construction of SQL expressions using table-bound or other selectable-bound columns:

select(mytable).where(mytable.c.somecolumn == 5)

Returns:: a ColumnCollection object.

attribute sqlalchemy.sql.expression.FromClause.description¶

A brief description of this FromClause.

Used primarily for error message formatting.

attribute sqlalchemy.sql.expression.FromClause.entity_namespace¶

Return a namespace used for name-based access in SQL expressions.

This is the namespace that is used to resolve “filter_by()” type expressions, such as:

stmt.filter_by(address='some address')

It defaults to the .c collection, however internally it can be overridden using the “entity_namespace” annotation to deliver alternative results.

attribute sqlalchemy.sql.expression.FromClause.exported_columns¶

A ColumnCollection that represents the “exported” columns of this Selectable.

The “exported” columns for a FromClause object are synonymous with the FromClause.columns collection.

New in version 1.4.

See also

Table.foreign_key_constraints

attribute sqlalchemy.sql.expression.FromClause.foreign_keys¶

Return the collection of ForeignKey marker objects which this FromClause references.

Each ForeignKey is a member of a Table-wide ForeignKeyConstraint.

See also

method sqlalchemy.sql.expression.FromClause.is_derived_from(fromclause: FromClause | None) → bool¶

Return True if this FromClause is ‘derived’ from the given FromClause.

An example would be an Alias of a Table is derived from that Table.

method sqlalchemy.sql.expression.FromClause.join(right: _FromClauseArgument, onclause: _ColumnExpressionArgument[bool] | None = None, isouter: bool = False, full: bool = False) → Join¶

Return a Join from this FromClause to another FromClause.

E.g.:

from sqlalchemy import join

j = user_table.join(address_table,
                user_table.c.id == address_table.c.user_id)
stmt = select(user_table).select_from(j)

would emit SQL along the lines of:

SELECT user.id, user.name FROM user
JOIN address ON user.id = address.user_id

Parameters:

right – the right side of the join; this is any FromClause object such as a Table object, and may also be a selectable-compatible object such as an ORM-mapped class.
onclause – a SQL expression representing the ON clause of the join. If left at None, FromClause.join() will attempt to join the two tables based on a foreign key relationship.
isouter – if True, render a LEFT OUTER JOIN, instead of JOIN.
full – if True, render a FULL OUTER JOIN, instead of LEFT OUTER JOIN. Implies FromClause.join.isouter.

See also

join() - standalone function

Join - the type of object produced

method sqlalchemy.sql.expression.FromClause.outerjoin(right: _FromClauseArgument, onclause: _ColumnExpressionArgument[bool] | None = None, full: bool = False) → Join¶

Return a Join from this FromClause to another FromClause, with the “isouter” flag set to True.

E.g.:

from sqlalchemy import outerjoin

j = user_table.outerjoin(address_table,
                user_table.c.id == address_table.c.user_id)

The above is equivalent to:

j = user_table.join(
    address_table,
    user_table.c.id == address_table.c.user_id,
    isouter=True)

Parameters:

right – the right side of the join; this is any FromClause object such as a Table object, and may also be a selectable-compatible object such as an ORM-mapped class.
onclause – a SQL expression representing the ON clause of the join. If left at None, FromClause.join() will attempt to join the two tables based on a foreign key relationship.
full – if True, render a FULL OUTER JOIN, instead of LEFT OUTER JOIN.

See also

FromClause.join()

Join

attribute sqlalchemy.sql.expression.FromClause.primary_key¶

Return the iterable collection of Column objects which comprise the primary key of this _selectable.FromClause.

For a Table object, this collection is represented by the PrimaryKeyConstraint which itself is an iterable collection of Column objects.

attribute sqlalchemy.sql.expression.FromClause.schema: str | None = None¶

Define the ‘schema’ attribute for this FromClause.

This is typically None for most objects except that of Table, where it is taken as the value of the Table.schema argument.

method sqlalchemy.sql.expression.FromClause.select() → Select¶

Return a SELECT of this FromClause.

e.g.:

stmt = some_table.select().where(some_table.c.id == 5)

See also

select() - general purpose method which allows for arbitrary column lists.

method sqlalchemy.sql.expression.FromClause.tablesample(sampling: float | Function[Any], name: str | None = None, seed: roles.ExpressionElementRole[Any] | None = None) → TableSample¶

Return a TABLESAMPLE alias of this FromClause.

The return value is the TableSample construct also provided by the top-level tablesample() function.

See also

tablesample() - usage guidelines and parameters

class sqlalchemy.sql.expression.GenerativeSelect¶

Base class for SELECT statements where additional elements can be added.

This serves as the base for Select and CompoundSelect where elements such as ORDER BY, GROUP BY can be added and column rendering can be controlled. Compare to TextualSelect, which, while it subclasses SelectBase and is also a SELECT construct, represents a fixed textual string which cannot be altered at this level, only wrapped as a subquery.

Members

fetch(), get_label_style(), group_by(), limit(), offset(), order_by(), set_label_style(), slice(), with_for_update()

Class signature

class sqlalchemy.sql.expression.GenerativeSelect (sqlalchemy.sql.expression.SelectBase, sqlalchemy.sql.expression.Generative)

method sqlalchemy.sql.expression.GenerativeSelect.fetch(count: _LimitOffsetType, with_ties: bool = False, percent: bool = False) → Self¶

Return a new selectable with the given FETCH FIRST criterion applied.

This is a numeric value which usually renders as FETCH {FIRST | NEXT} [ count ] {ROW | ROWS} {ONLY | WITH TIES} expression in the resulting select. This functionality is is currently implemented for Oracle, PostgreSQL, MSSQL.

Use GenerativeSelect.offset() to specify the offset.

Note

The GenerativeSelect.fetch() method will replace any clause applied with GenerativeSelect.limit().

New in version 1.4.

Parameters:

count – an integer COUNT parameter, or a SQL expression that provides an integer result. When percent=True this will represent the percentage of rows to return, not the absolute value. Pass None to reset it.
with_ties – When True, the WITH TIES option is used to return any additional rows that tie for the last place in the result set according to the ORDER BY clause. The ORDER BY may be mandatory in this case. Defaults to False
percent – When True, count represents the percentage of the total number of selected rows to return. Defaults to False

See also

method sqlalchemy.sql.expression.GenerativeSelect.get_label_style() → SelectLabelStyle¶: Retrieve the current label style.

New in version 1.4.

method sqlalchemy.sql.expression.GenerativeSelect.group_by(_GenerativeSelect__first: Literal[None, _NoArg.NO_ARG] | _ColumnExpressionOrStrLabelArgument[Any] = _NoArg.NO_ARG, *clauses: _ColumnExpressionOrStrLabelArgument[Any]) → Self¶

Return a new selectable with the given list of GROUP BY criterion applied.

All existing GROUP BY settings can be suppressed by passing None.

e.g.:

stmt = select(table.c.name, func.max(table.c.stat)).\
group_by(table.c.name)

Parameters:: *clauses – a series of ColumnElement constructs which will be used to generate an GROUP BY clause.

Ordering or Grouping by a Label - in the SQLAlchemy Unified Tutorial

method sqlalchemy.sql.expression.GenerativeSelect.limit(limit: _LimitOffsetType) → Self¶

Return a new selectable with the given LIMIT criterion applied.

This is a numerical value which usually renders as a LIMIT expression in the resulting select. Backends that don’t support LIMIT will attempt to provide similar functionality.

Note

The GenerativeSelect.limit() method will replace any clause applied with GenerativeSelect.fetch().

Parameters:: limit – an integer LIMIT parameter, or a SQL expression that provides an integer result. Pass None to reset it.

See also

method sqlalchemy.sql.expression.GenerativeSelect.offset(offset: _LimitOffsetType) → Self¶

Return a new selectable with the given OFFSET criterion applied.

This is a numeric value which usually renders as an OFFSET expression in the resulting select. Backends that don’t support OFFSET will attempt to provide similar functionality.

Parameters:: offset – an integer OFFSET parameter, or a SQL expression that provides an integer result. Pass None to reset it.

See also

method sqlalchemy.sql.expression.GenerativeSelect.order_by(_GenerativeSelect__first: Literal[None, _NoArg.NO_ARG] | _ColumnExpressionOrStrLabelArgument[Any] = _NoArg.NO_ARG, *clauses: _ColumnExpressionOrStrLabelArgument[Any]) → Self¶

Return a new selectable with the given list of ORDER BY criteria applied.

e.g.:

stmt = select(table).order_by(table.c.id, table.c.name)

Calling this method multiple times is equivalent to calling it once with all the clauses concatenated. All existing ORDER BY criteria may be cancelled by passing None by itself. New ORDER BY criteria may then be added by invoking Query.order_by() again, e.g.:

# will erase all ORDER BY and ORDER BY new_col alone
stmt = stmt.order_by(None).order_by(new_col)

Parameters:: *clauses – a series of ColumnElement constructs which will be used to generate an ORDER BY clause.

Ordering or Grouping by a Label - in the SQLAlchemy Unified Tutorial

method sqlalchemy.sql.expression.GenerativeSelect.set_label_style(style: SelectLabelStyle) → Self¶

Return a new selectable with the specified label style.

There are three “label styles” available, SelectLabelStyle.LABEL_STYLE_DISAMBIGUATE_ONLY, SelectLabelStyle.LABEL_STYLE_TABLENAME_PLUS_COL, and SelectLabelStyle.LABEL_STYLE_NONE. The default style is SelectLabelStyle.LABEL_STYLE_TABLENAME_PLUS_COL.

In modern SQLAlchemy, there is not generally a need to change the labeling style, as per-expression labels are more effectively used by making use of the ColumnElement.label() method. In past versions, LABEL_STYLE_TABLENAME_PLUS_COL was used to disambiguate same-named columns from different tables, aliases, or subqueries; the newer LABEL_STYLE_DISAMBIGUATE_ONLY now applies labels only to names that conflict with an existing name so that the impact of this labeling is minimal.

The rationale for disambiguation is mostly so that all column expressions are available from a given FromClause.c collection when a subquery is created.

New in version 1.4: - the GenerativeSelect.set_label_style() method replaces the previous combination of .apply_labels(), .with_labels() and use_labels=True methods and/or parameters.

See also

LABEL_STYLE_DISAMBIGUATE_ONLY

LABEL_STYLE_TABLENAME_PLUS_COL

LABEL_STYLE_NONE

LABEL_STYLE_DEFAULT

method sqlalchemy.sql.expression.GenerativeSelect.slice(start: int, stop: int) → Self¶

Apply LIMIT / OFFSET to this statement based on a slice.

The start and stop indices behave like the argument to Python’s built-in range() function. This method provides an alternative to using LIMIT/OFFSET to get a slice of the query.

For example,

stmt = select(User).order_by(User).id.slice(1, 3)

renders as

SELECT users.id AS users_id,
       users.name AS users_name
FROM users ORDER BY users.id
LIMIT ? OFFSET ?
(2, 1)

Note

The GenerativeSelect.slice() method will replace any clause applied with GenerativeSelect.fetch().

New in version 1.4: Added the GenerativeSelect.slice() method generalized from the ORM.

See also

exported_columns, is_derived_from()

method sqlalchemy.sql.expression.GenerativeSelect.with_for_update(*, nowait: bool = False, read: bool = False, of: _ForUpdateOfArgument | None = None, skip_locked: bool = False, key_share: bool = False) → Self¶

Specify a FOR UPDATE clause for this GenerativeSelect.

E.g.:

stmt = select(table).with_for_update(nowait=True)

On a database like PostgreSQL or Oracle, the above would render a statement like:

SELECT table.a, table.b FROM table FOR UPDATE NOWAIT

on other backends, the nowait option is ignored and instead would produce:

SELECT table.a, table.b FROM table FOR UPDATE

When called with no arguments, the statement will render with the suffix FOR UPDATE. Additional arguments can then be provided which allow for common database-specific variants.

Parameters:

nowait – boolean; will render FOR UPDATE NOWAIT on Oracle and PostgreSQL dialects.
read – boolean; will render LOCK IN SHARE MODE on MySQL, FOR SHARE on PostgreSQL. On PostgreSQL, when combined with nowait, will render FOR SHARE NOWAIT.
of – SQL expression or list of SQL expression elements, (typically Column objects or a compatible expression, for some backends may also be a table expression) which will render into a FOR UPDATE OF clause; supported by PostgreSQL, Oracle, some MySQL versions and possibly others. May render as a table or as a column depending on backend.
skip_locked – boolean, will render FOR UPDATE SKIP LOCKED on Oracle and PostgreSQL dialects or FOR SHARE SKIP LOCKED if read=True is also specified.
key_share – boolean, will render FOR NO KEY UPDATE, or if combined with read=True will render FOR KEY SHARE, on the PostgreSQL dialect.

class sqlalchemy.sql.expression.HasCTE¶

Mixin that declares a class to include CTE support.

Members

add_cte(), cte()

Class signature

class sqlalchemy.sql.expression.HasCTE (sqlalchemy.sql.roles.HasCTERole, sqlalchemy.sql.expression.SelectsRows)

method sqlalchemy.sql.expression.HasCTE.add_cte(*ctes: CTE, nest_here: bool = False) → Self¶

Add one or more CTE constructs to this statement.

This method will associate the given CTE constructs with the parent statement such that they will each be unconditionally rendered in the WITH clause of the final statement, even if not referenced elsewhere within the statement or any sub-selects.

The optional HasCTE.add_cte.nest_here parameter when set to True will have the effect that each given CTE will render in a WITH clause rendered directly along with this statement, rather than being moved to the top of the ultimate rendered statement, even if this statement is rendered as a subquery within a larger statement.

This method has two general uses. One is to embed CTE statements that serve some purpose without being referenced explicitly, such as the use case of embedding a DML statement such as an INSERT or UPDATE as a CTE inline with a primary statement that may draw from its results indirectly. The other is to provide control over the exact placement of a particular series of CTE constructs that should remain rendered directly in terms of a particular statement that may be nested in a larger statement.

E.g.:

from sqlalchemy import table, column, select
t = table('t', column('c1'), column('c2'))

ins = t.insert().values({"c1": "x", "c2": "y"}).cte()

stmt = select(t).add_cte(ins)

Would render:

WITH anon_1 AS
(INSERT INTO t (c1, c2) VALUES (:param_1, :param_2))
SELECT t.c1, t.c2
FROM t

Above, the “anon_1” CTE is not referenced in the SELECT statement, however still accomplishes the task of running an INSERT statement.

Similarly in a DML-related context, using the PostgreSQL Insert construct to generate an “upsert”:

from sqlalchemy import table, column
from sqlalchemy.dialects.postgresql import insert

t = table("t", column("c1"), column("c2"))

delete_statement_cte = (
    t.delete().where(t.c.c1 < 1).cte("deletions")
)

insert_stmt = insert(t).values({"c1": 1, "c2": 2})
update_statement = insert_stmt.on_conflict_do_update(
    index_elements=[t.c.c1],
    set_={
        "c1": insert_stmt.excluded.c1,
        "c2": insert_stmt.excluded.c2,
    },
).add_cte(delete_statement_cte)

print(update_statement)

The above statement renders as:

WITH deletions AS
(DELETE FROM t WHERE t.c1 < %(c1_1)s)
INSERT INTO t (c1, c2) VALUES (%(c1)s, %(c2)s)
ON CONFLICT (c1) DO UPDATE SET c1 = excluded.c1, c2 = excluded.c2

New in version 1.4.21.

Parameters:

*ctes –
zero or more CTE constructs.

Changed in version 2.0: Multiple CTE instances are accepted
nest_here –
if True, the given CTE or CTEs will be rendered as though they specified the HasCTE.cte.nesting flag to True when they were added to this HasCTE. Assuming the given CTEs are not referenced in an outer-enclosing statement as well, the CTEs given should render at the level of this statement when this flag is given.

New in version 2.0.

See also

HasCTE.cte.nesting

method sqlalchemy.sql.expression.HasCTE.cte(name: str | None = None, recursive: bool = False, nesting: bool = False) → CTE¶

Return a new CTE, or Common Table Expression instance.

Common table expressions are a SQL standard whereby SELECT statements can draw upon secondary statements specified along with the primary statement, using a clause called “WITH”. Special semantics regarding UNION can also be employed to allow “recursive” queries, where a SELECT statement can draw upon the set of rows that have previously been selected.

CTEs can also be applied to DML constructs UPDATE, INSERT and DELETE on some databases, both as a source of CTE rows when combined with RETURNING, as well as a consumer of CTE rows.

SQLAlchemy detects CTE objects, which are treated similarly to Alias objects, as special elements to be delivered to the FROM clause of the statement as well as to a WITH clause at the top of the statement.

For special prefixes such as PostgreSQL “MATERIALIZED” and “NOT MATERIALIZED”, the CTE.prefix_with() method may be used to establish these.

Changed in version 1.3.13: Added support for prefixes. In particular - MATERIALIZED and NOT MATERIALIZED.

Parameters:

name – name given to the common table expression. Like FromClause.alias(), the name can be left as None in which case an anonymous symbol will be used at query compile time.
recursive – if True, will render WITH RECURSIVE. A recursive common table expression is intended to be used in conjunction with UNION ALL in order to derive rows from those already selected.
nesting –
if True, will render the CTE locally to the statement in which it is referenced. For more complex scenarios, the HasCTE.add_cte() method using the HasCTE.add_cte.nest_here parameter may also be used to more carefully control the exact placement of a particular CTE.

New in version 1.4.24.

See also

HasCTE.add_cte()

The following examples include two from PostgreSQL’s documentation at https://www.postgresql.org/docs/current/static/queries-with.html, as well as additional examples.

Example 1, non recursive:

from sqlalchemy import (Table, Column, String, Integer,
                        MetaData, select, func)

metadata = MetaData()

orders = Table('orders', metadata,
    Column('region', String),
    Column('amount', Integer),
    Column('product', String),
    Column('quantity', Integer)
)

regional_sales = select(
                    orders.c.region,
                    func.sum(orders.c.amount).label('total_sales')
                ).group_by(orders.c.region).cte("regional_sales")


top_regions = select(regional_sales.c.region).\
        where(
            regional_sales.c.total_sales >
            select(
                func.sum(regional_sales.c.total_sales) / 10
            )
        ).cte("top_regions")

statement = select(
            orders.c.region,
            orders.c.product,
            func.sum(orders.c.quantity).label("product_units"),
            func.sum(orders.c.amount).label("product_sales")
    ).where(orders.c.region.in_(
        select(top_regions.c.region)
    )).group_by(orders.c.region, orders.c.product)

result = conn.execute(statement).fetchall()

Example 2, WITH RECURSIVE:

from sqlalchemy import (Table, Column, String, Integer,
                        MetaData, select, func)

metadata = MetaData()

parts = Table('parts', metadata,
    Column('part', String),
    Column('sub_part', String),
    Column('quantity', Integer),
)

included_parts = select(\
    parts.c.sub_part, parts.c.part, parts.c.quantity\
    ).\
    where(parts.c.part=='our part').\
    cte(recursive=True)


incl_alias = included_parts.alias()
parts_alias = parts.alias()
included_parts = included_parts.union_all(
    select(
        parts_alias.c.sub_part,
        parts_alias.c.part,
        parts_alias.c.quantity
    ).\
    where(parts_alias.c.part==incl_alias.c.sub_part)
)

statement = select(
            included_parts.c.sub_part,
            func.sum(included_parts.c.quantity).
              label('total_quantity')
        ).\
        group_by(included_parts.c.sub_part)

result = conn.execute(statement).fetchall()

Example 3, an upsert using UPDATE and INSERT with CTEs:

from datetime import date
from sqlalchemy import (MetaData, Table, Column, Integer,
                        Date, select, literal, and_, exists)

metadata = MetaData()

visitors = Table('visitors', metadata,
    Column('product_id', Integer, primary_key=True),
    Column('date', Date, primary_key=True),
    Column('count', Integer),
)

# add 5 visitors for the product_id == 1
product_id = 1
day = date.today()
count = 5

update_cte = (
    visitors.update()
    .where(and_(visitors.c.product_id == product_id,
                visitors.c.date == day))
    .values(count=visitors.c.count + count)
    .returning(literal(1))
    .cte('update_cte')
)

upsert = visitors.insert().from_select(
    [visitors.c.product_id, visitors.c.date, visitors.c.count],
    select(literal(product_id), literal(day), literal(count))
        .where(~exists(update_cte.select()))
)

connection.execute(upsert)

Example 4, Nesting CTE (SQLAlchemy 1.4.24 and above):

value_a = select(
    literal("root").label("n")
).cte("value_a")

# A nested CTE with the same name as the root one
value_a_nested = select(
    literal("nesting").label("n")
).cte("value_a", nesting=True)

# Nesting CTEs takes ascendency locally
# over the CTEs at a higher level
value_b = select(value_a_nested.c.n).cte("value_b")

value_ab = select(value_a.c.n.label("a"), value_b.c.n.label("b"))

The above query will render the second CTE nested inside the first, shown with inline parameters below as:

WITH
    value_a AS
        (SELECT 'root' AS n),
    value_b AS
        (WITH value_a AS
            (SELECT 'nesting' AS n)
        SELECT value_a.n AS n FROM value_a)
SELECT value_a.n AS a, value_b.n AS b
FROM value_a, value_b

The same CTE can be set up using the HasCTE.add_cte() method as follows (SQLAlchemy 2.0 and above):

value_a = select(
    literal("root").label("n")
).cte("value_a")

# A nested CTE with the same name as the root one
value_a_nested = select(
    literal("nesting").label("n")
).cte("value_a")

# Nesting CTEs takes ascendency locally
# over the CTEs at a higher level
value_b = (
    select(value_a_nested.c.n).
    add_cte(value_a_nested, nest_here=True).
    cte("value_b")
)

value_ab = select(value_a.c.n.label("a"), value_b.c.n.label("b"))

Example 5, Non-Linear CTE (SQLAlchemy 1.4.28 and above):

edge = Table(
    "edge",
    metadata,
    Column("id", Integer, primary_key=True),
    Column("left", Integer),
    Column("right", Integer),
)

root_node = select(literal(1).label("node")).cte(
    "nodes", recursive=True
)

left_edge = select(edge.c.left).join(
    root_node, edge.c.right == root_node.c.node
)
right_edge = select(edge.c.right).join(
    root_node, edge.c.left == root_node.c.node
)

subgraph_cte = root_node.union(left_edge, right_edge)

subgraph = select(subgraph_cte)

The above query will render 2 UNIONs inside the recursive CTE:

WITH RECURSIVE nodes(node) AS (
        SELECT 1 AS node
    UNION
        SELECT edge."left" AS "left"
        FROM edge JOIN nodes ON edge."right" = nodes.node
    UNION
        SELECT edge."right" AS "right"
        FROM edge JOIN nodes ON edge."left" = nodes.node
)
SELECT nodes.node FROM nodes

See also

Query.cte() - ORM version of HasCTE.cte().

class sqlalchemy.sql.expression.HasPrefixes¶

Members

prefix_with()

method sqlalchemy.sql.expression.HasPrefixes.prefix_with(*prefixes: _TextCoercedExpressionArgument[Any], dialect: str = '*') → Self¶

Add one or more expressions following the statement keyword, i.e. SELECT, INSERT, UPDATE, or DELETE. Generative.

This is used to support backend-specific prefix keywords such as those provided by MySQL.

E.g.:

stmt = table.insert().prefix_with("LOW_PRIORITY", dialect="mysql")

# MySQL 5.7 optimizer hints
stmt = select(table).prefix_with(
    "/*+ BKA(t1) */", dialect="mysql")

Multiple prefixes can be specified by multiple calls to HasPrefixes.prefix_with().

Parameters:

*prefixes – textual or ClauseElement construct which will be rendered following the INSERT, UPDATE, or DELETE keyword.
dialect – optional string dialect name which will limit rendering of this prefix to only that dialect.

class sqlalchemy.sql.expression.HasSuffixes¶

Members

suffix_with()

method sqlalchemy.sql.expression.HasSuffixes.suffix_with(*suffixes: _TextCoercedExpressionArgument[Any], dialect: str = '*') → Self¶

Add one or more expressions following the statement as a whole.

This is used to support backend-specific suffix keywords on certain constructs.

E.g.:

stmt = select(col1, col2).cte().suffix_with(
    "cycle empno set y_cycle to 1 default 0", dialect="oracle")

Multiple suffixes can be specified by multiple calls to HasSuffixes.suffix_with().

Parameters:

*suffixes – textual or ClauseElement construct which will be rendered following the target clause.
dialect – Optional string dialect name which will limit rendering of this suffix to only that dialect.

class sqlalchemy.sql.expression.Join¶

Represent a JOIN construct between two FromClause elements.

The public constructor function for Join is the module-level join() function, as well as the FromClause.join() method of any FromClause (e.g. such as Table).

See also

join()

FromClause.join()

Members

__init__(), description, is_derived_from(), select(), self_group()

Class signature

class sqlalchemy.sql.expression.Join (sqlalchemy.sql.roles.DMLTableRole, sqlalchemy.sql.expression.FromClause)

method sqlalchemy.sql.expression.Join.__init__(left: _FromClauseArgument, right: _FromClauseArgument, onclause: _OnClauseArgument | None = None, isouter: bool = False, full: bool = False)¶

Construct a new Join.

The usual entrypoint here is the join() function or the FromClause.join() method of any FromClause object.

attribute sqlalchemy.sql.expression.Join.description¶

method sqlalchemy.sql.expression.Join.is_derived_from(fromclause: FromClause | None) → bool¶

Return True if this FromClause is ‘derived’ from the given FromClause.

An example would be an Alias of a Table is derived from that Table.

method sqlalchemy.sql.expression.Join.select() → Select¶

Create a Select from this Join.

E.g.:

stmt = table_a.join(table_b, table_a.c.id == table_b.c.a_id)

stmt = stmt.select()

The above will produce a SQL string resembling:

SELECT table_a.id, table_a.col, table_b.id, table_b.a_id
FROM table_a JOIN table_b ON table_a.id = table_b.a_id

method sqlalchemy.sql.expression.Join.self_group(against: OperatorType | None = None) → FromGrouping¶

Apply a ‘grouping’ to this ClauseElement.

This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by select() constructs when placed into the FROM clause of another select(). (Note that subqueries should be normally created using the Select.alias() method, as many platforms require nested SELECT statements to be named).

As expressions are composed together, the application of self_group() is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like x OR (y AND z) - AND takes precedence over OR.

The base self_group() method of ClauseElement just returns self.

class sqlalchemy.sql.expression.Lateral¶

Represent a LATERAL subquery.

This object is constructed from the lateral() module level function as well as the FromClause.lateral() method available on all FromClause subclasses.

While LATERAL is part of the SQL standard, currently only more recent PostgreSQL versions provide support for this keyword.

See also

LATERAL correlation - overview of usage.

Members

inherit_cache

Class signature

class sqlalchemy.sql.expression.Lateral (sqlalchemy.sql.expression.FromClauseAlias, sqlalchemy.sql.expression.LateralFromClause)

attribute sqlalchemy.sql.expression.Lateral.inherit_cache: bool | None = True¶

Indicate if this HasCacheKey instance should make use of the cache key generation scheme used by its immediate superclass.

The attribute defaults to None, which indicates that a construct has not yet taken into account whether or not its appropriate for it to participate in caching; this is functionally equivalent to setting the value to False, except that a warning is also emitted.

This flag can be set to True on a particular class, if the SQL that corresponds to the object does not change based on attributes which are local to this class, and not its superclass.

See also

Enabling Caching Support for Custom Constructs - General guideslines for setting the HasCacheKey.inherit_cache attribute for third-party or user defined SQL constructs.

class sqlalchemy.sql.expression.ReturnsRows¶

The base-most class for Core constructs that have some concept of columns that can represent rows.

While the SELECT statement and TABLE are the primary things we think of in this category, DML like INSERT, UPDATE and DELETE can also specify RETURNING which means they can be used in CTEs and other forms, and PostgreSQL has functions that return rows also.

New in version 1.4.

Members

Class signature

class sqlalchemy.sql.expression.ReturnsRows (sqlalchemy.sql.roles.ReturnsRowsRole, sqlalchemy.sql.expression.DQLDMLClauseElement)

attribute sqlalchemy.sql.expression.ReturnsRows.exported_columns¶

A ColumnCollection that represents the “exported” columns of this ReturnsRows.

The “exported” columns represent the collection of ColumnElement expressions that are rendered by this SQL construct. There are primary varieties which are the “FROM clause columns” of a FROM clause, such as a table, join, or subquery, the “SELECTed columns”, which are the columns in the “columns clause” of a SELECT statement, and the RETURNING columns in a DML statement..

New in version 1.4.

See also

SelectBase.scalar_subquery()

method sqlalchemy.sql.expression.ReturnsRows.is_derived_from(fromclause: FromClause | None) → bool¶

Return True if this ReturnsRows is ‘derived’ from the given FromClause.

An example would be an Alias of a Table is derived from that Table.

class sqlalchemy.sql.expression.ScalarSelect¶

Represent a scalar subquery.

A ScalarSelect is created by invoking the SelectBase.scalar_subquery() method. The object then participates in other SQL expressions as a SQL column expression within the ColumnElement hierarchy.

See also

Scalar and Correlated Subqueries - in the 2.0 tutorial

Members

correlate(), correlate_except(), inherit_cache, self_group(), where()

Class signature

class sqlalchemy.sql.expression.ScalarSelect (sqlalchemy.sql.roles.InElementRole, sqlalchemy.sql.expression.Generative, sqlalchemy.sql.expression.GroupedElement, sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.ScalarSelect.correlate(*fromclauses: Literal[None, False] | _FromClauseArgument) → Self¶

Return a new ScalarSelect which will correlate the given FROM clauses to that of an enclosing Select.

This method is mirrored from the Select.correlate() method of the underlying Select. The method applies the :meth:_sql.Select.correlate` method, then returns a new ScalarSelect against that statement.

New in version 1.4: Previously, the ScalarSelect.correlate() method was only available from Select.

Parameters:: *fromclauses – a list of one or more FromClause constructs, or other compatible constructs (i.e. ORM-mapped classes) to become part of the correlate collection.

See also

ScalarSelect.correlate_except()

Scalar and Correlated Subqueries - in the 2.0 tutorial

method sqlalchemy.sql.expression.ScalarSelect.correlate_except(*fromclauses: Literal[None, False] | _FromClauseArgument) → Self¶

Return a new ScalarSelect which will omit the given FROM clauses from the auto-correlation process.

This method is mirrored from the Select.correlate_except() method of the underlying Select. The method applies the :meth:_sql.Select.correlate_except` method, then returns a new ScalarSelect against that statement.

New in version 1.4: Previously, the ScalarSelect.correlate_except() method was only available from Select.

Parameters:: *fromclauses – a list of one or more FromClause constructs, or other compatible constructs (i.e. ORM-mapped classes) to become part of the correlate-exception collection.

See also

ScalarSelect.correlate()

Scalar and Correlated Subqueries - in the 2.0 tutorial

attribute sqlalchemy.sql.expression.ScalarSelect.inherit_cache: bool | None = True¶

Indicate if this HasCacheKey instance should make use of the cache key generation scheme used by its immediate superclass.

The attribute defaults to None, which indicates that a construct has not yet taken into account whether or not its appropriate for it to participate in caching; this is functionally equivalent to setting the value to False, except that a warning is also emitted.

This flag can be set to True on a particular class, if the SQL that corresponds to the object does not change based on attributes which are local to this class, and not its superclass.

See also

Enabling Caching Support for Custom Constructs - General guideslines for setting the HasCacheKey.inherit_cache attribute for third-party or user defined SQL constructs.

method sqlalchemy.sql.expression.ScalarSelect.self_group(against: OperatorType | None = None) → ColumnElement[Any]¶

Apply a ‘grouping’ to this ClauseElement.

This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by select() constructs when placed into the FROM clause of another select(). (Note that subqueries should be normally created using the Select.alias() method, as many platforms require nested SELECT statements to be named).

As expressions are composed together, the application of self_group() is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like x OR (y AND z) - AND takes precedence over OR.

The base self_group() method of ClauseElement just returns self.

method sqlalchemy.sql.expression.ScalarSelect.where(crit: _ColumnExpressionArgument[bool]) → Self¶: Apply a WHERE clause to the SELECT statement referred to by this ScalarSelect.

class sqlalchemy.sql.expression.Select¶

Represents a SELECT statement.

The Select object is normally constructed using the select() function. See that function for details.

See also

select()

Using SELECT Statements - in the 2.0 tutorial

Members

__init__(), add_columns(), add_cte(), alias(), as_scalar(), c, column(), column_descriptions, columns_clause_froms, correlate(), correlate_except(), corresponding_column(), cte(), distinct(), except_(), except_all(), execution_options(), exists(), exported_columns, fetch(), filter(), filter_by(), from_statement(), froms, get_children(), get_execution_options(), get_final_froms(), get_label_style(), group_by(), having(), inherit_cache, inner_columns, intersect(), intersect_all(), is_derived_from(), join(), join_from(), label(), lateral(), limit(), offset(), options(), order_by(), outerjoin(), outerjoin_from(), prefix_with(), reduce_columns(), replace_selectable(), scalar_subquery(), select(), select_from(), selected_columns, self_group(), set_label_style(), slice(), subquery(), suffix_with(), union(), union_all(), where(), whereclause, with_for_update(), with_hint(), with_only_columns(), with_statement_hint()

Class signature

class sqlalchemy.sql.expression.Select (sqlalchemy.sql.expression.HasPrefixes, sqlalchemy.sql.expression.HasSuffixes, sqlalchemy.sql.expression.HasHints, sqlalchemy.sql.expression.HasCompileState, sqlalchemy.sql.expression._SelectFromElements, sqlalchemy.sql.expression.GenerativeSelect, sqlalchemy.sql.expression.TypedReturnsRows)

method sqlalchemy.sql.expression.Select.__init__(*entities: _ColumnsClauseArgument[Any])¶

Construct a new Select.

The public constructor for Select is the select() function.

method sqlalchemy.sql.expression.Select.add_columns(*entities: _ColumnsClauseArgument[Any]) → Select[Any]¶

Return a new select() construct with the given entities appended to its columns clause.

E.g.:

my_select = my_select.add_columns(table.c.new_column)

The original expressions in the columns clause remain in place. To replace the original expressions with new ones, see the method Select.with_only_columns().

Parameters:: *entities – column, table, or other entity expressions to be added to the columns clause

See also

Select.with_only_columns() - replaces existing expressions rather than appending.

Selecting Multiple ORM Entities Simultaneously - ORM-centric example

method sqlalchemy.sql.expression.Select.add_cte(*ctes: CTE, nest_here: bool = False) → Self¶

inherited from the HasCTE.add_cte() method of HasCTE

Add one or more CTE constructs to this statement.

This method will associate the given CTE constructs with the parent statement such that they will each be unconditionally rendered in the WITH clause of the final statement, even if not referenced elsewhere within the statement or any sub-selects.

The optional HasCTE.add_cte.nest_here parameter when set to True will have the effect that each given CTE will render in a WITH clause rendered directly along with this statement, rather than being moved to the top of the ultimate rendered statement, even if this statement is rendered as a subquery within a larger statement.

This method has two general uses. One is to embed CTE statements that serve some purpose without being referenced explicitly, such as the use case of embedding a DML statement such as an INSERT or UPDATE as a CTE inline with a primary statement that may draw from its results indirectly. The other is to provide control over the exact placement of a particular series of CTE constructs that should remain rendered directly in terms of a particular statement that may be nested in a larger statement.

E.g.:

from sqlalchemy import table, column, select
t = table('t', column('c1'), column('c2'))

ins = t.insert().values({"c1": "x", "c2": "y"}).cte()

stmt = select(t).add_cte(ins)

Would render:

WITH anon_1 AS
(INSERT INTO t (c1, c2) VALUES (:param_1, :param_2))
SELECT t.c1, t.c2
FROM t

Above, the “anon_1” CTE is not referenced in the SELECT statement, however still accomplishes the task of running an INSERT statement.

Similarly in a DML-related context, using the PostgreSQL Insert construct to generate an “upsert”:

from sqlalchemy import table, column
from sqlalchemy.dialects.postgresql import insert

t = table("t", column("c1"), column("c2"))

delete_statement_cte = (
    t.delete().where(t.c.c1 < 1).cte("deletions")
)

insert_stmt = insert(t).values({"c1": 1, "c2": 2})
update_statement = insert_stmt.on_conflict_do_update(
    index_elements=[t.c.c1],
    set_={
        "c1": insert_stmt.excluded.c1,
        "c2": insert_stmt.excluded.c2,
    },
).add_cte(delete_statement_cte)

print(update_statement)

The above statement renders as:

WITH deletions AS
(DELETE FROM t WHERE t.c1 < %(c1_1)s)
INSERT INTO t (c1, c2) VALUES (%(c1)s, %(c2)s)
ON CONFLICT (c1) DO UPDATE SET c1 = excluded.c1, c2 = excluded.c2

New in version 1.4.21.

Parameters:

*ctes –
zero or more CTE constructs.

Changed in version 2.0: Multiple CTE instances are accepted
nest_here –
if True, the given CTE or CTEs will be rendered as though they specified the HasCTE.cte.nesting flag to True when they were added to this HasCTE. Assuming the given CTEs are not referenced in an outer-enclosing statement as well, the CTEs given should render at the level of this statement when this flag is given.

New in version 2.0.

See also

HasCTE.cte.nesting

method sqlalchemy.sql.expression.Select.alias(name: str | None = None, flat: bool = False) → Subquery¶

inherited from the SelectBase.alias() method of SelectBase

Return a named subquery against this SelectBase.

For a SelectBase (as opposed to a FromClause), this returns a Subquery object which behaves mostly the same as the Alias object that is used with a FromClause.

Changed in version 1.4: The SelectBase.alias() method is now a synonym for the SelectBase.subquery() method.

method sqlalchemy.sql.expression.Select.as_scalar() → ScalarSelect[Any]¶: inherited from the SelectBase.as_scalar() method of SelectBase

Deprecated since version 1.4: The SelectBase.as_scalar() method is deprecated and will be removed in a future release. Please refer to SelectBase.scalar_subquery().

attribute sqlalchemy.sql.expression.Select.c¶: inherited from the SelectBase.c attribute of SelectBase

Deprecated since version 1.4: The SelectBase.c and SelectBase.columns attributes are deprecated and will be removed in a future release; these attributes implicitly create a subquery that should be explicit. Please call SelectBase.subquery() first in order to create a subquery, which then contains this attribute. To access the columns that this SELECT object SELECTs from, use the SelectBase.selected_columns attribute.

method sqlalchemy.sql.expression.Select.column(column: _ColumnsClauseArgument[Any]) → Select[Any]¶

Return a new select() construct with the given column expression added to its columns clause.

Deprecated since version 1.4: The Select.column() method is deprecated and will be removed in a future release. Please use Select.add_columns()

E.g.:

my_select = my_select.column(table.c.new_column)

See the documentation for Select.with_only_columns() for guidelines on adding /replacing the columns of a Select object.

attribute sqlalchemy.sql.expression.Select.column_descriptions¶

Return a plugin-enabled ‘column descriptions’ structure referring to the columns which are SELECTed by this statement.

This attribute is generally useful when using the ORM, as an extended structure which includes information about mapped entities is returned. The section Inspecting entities and columns from ORM-enabled SELECT and DML statements contains more background.

For a Core-only statement, the structure returned by this accessor is derived from the same objects that are returned by the Select.selected_columns accessor, formatted as a list of dictionaries which contain the keys name, type and expr, which indicate the column expressions to be selected:

>>> stmt = select(user_table)
>>> stmt.column_descriptions
[
    {
        'name': 'id',
        'type': Integer(),
        'expr': Column('id', Integer(), ...)},
    {
        'name': 'name',
        'type': String(length=30),
        'expr': Column('name', String(length=30), ...)}
]

Changed in version 1.4.33: The Select.column_descriptions attribute returns a structure for a Core-only set of entities, not just ORM-only entities.

See also

UpdateBase.entity_description - entity information for an insert(), update(), or delete()

Inspecting entities and columns from ORM-enabled SELECT and DML statements - ORM background

attribute sqlalchemy.sql.expression.Select.columns_clause_froms¶: Return the set of FromClause objects implied by the columns clause of this SELECT statement.

New in version 1.4.23.

See also

Select.froms - “final” FROM list taking the full statement into account

Select.with_only_columns() - makes use of this collection to set up a new FROM list

method sqlalchemy.sql.expression.Select.correlate(*fromclauses: Literal[None, False] | _FromClauseArgument) → Self¶

Return a new Select which will correlate the given FROM clauses to that of an enclosing Select.

Calling this method turns off the Select object’s default behavior of “auto-correlation”. Normally, FROM elements which appear in a Select that encloses this one via its WHERE clause, ORDER BY, HAVING or columns clause will be omitted from this Select object’s FROM clause. Setting an explicit correlation collection using the Select.correlate() method provides a fixed list of FROM objects that can potentially take place in this process.

When Select.correlate() is used to apply specific FROM clauses for correlation, the FROM elements become candidates for correlation regardless of how deeply nested this Select object is, relative to an enclosing Select which refers to the same FROM object. This is in contrast to the behavior of “auto-correlation” which only correlates to an immediate enclosing Select. Multi-level correlation ensures that the link between enclosed and enclosing Select is always via at least one WHERE/ORDER BY/HAVING/columns clause in order for correlation to take place.

If None is passed, the Select object will correlate none of its FROM entries, and all will render unconditionally in the local FROM clause.

Parameters:: *fromclauses – one or more FromClause or other FROM-compatible construct such as an ORM mapped entity to become part of the correlate collection; alternatively pass a single value None to remove all existing correlations.

See also

Select.correlate_except()

Scalar and Correlated Subqueries

method sqlalchemy.sql.expression.Select.correlate_except(*fromclauses: Literal[None, False] | _FromClauseArgument) → Self¶

Return a new Select which will omit the given FROM clauses from the auto-correlation process.

Calling Select.correlate_except() turns off the Select object’s default behavior of “auto-correlation” for the given FROM elements. An element specified here will unconditionally appear in the FROM list, while all other FROM elements remain subject to normal auto-correlation behaviors.

If None is passed, or no arguments are passed, the Select object will correlate all of its FROM entries.

Parameters:: *fromclauses – a list of one or more FromClause constructs, or other compatible constructs (i.e. ORM-mapped classes) to become part of the correlate-exception collection.

See also

Select.correlate()

Scalar and Correlated Subqueries

method sqlalchemy.sql.expression.Select.corresponding_column(column: KeyedColumnElement[Any], require_embedded: bool = False) → KeyedColumnElement[Any] | None¶

inherited from the Selectable.corresponding_column() method of Selectable

Given a ColumnElement, return the exported ColumnElement object from the Selectable.exported_columns collection of this Selectable which corresponds to that original ColumnElement via a common ancestor column.

Parameters:

column – the target ColumnElement to be matched.
require_embedded – only return corresponding columns for the given ColumnElement, if the given ColumnElement is actually present within a sub-element of this Selectable. Normally the column will match if it merely shares a common ancestor with one of the exported columns of this Selectable.

See also

Selectable.exported_columns - the ColumnCollection that is used for the operation.

ColumnCollection.corresponding_column() - implementation method.

method sqlalchemy.sql.expression.Select.cte(name: str | None = None, recursive: bool = False, nesting: bool = False) → CTE¶

inherited from the HasCTE.cte() method of HasCTE

Return a new CTE, or Common Table Expression instance.

Common table expressions are a SQL standard whereby SELECT statements can draw upon secondary statements specified along with the primary statement, using a clause called “WITH”. Special semantics regarding UNION can also be employed to allow “recursive” queries, where a SELECT statement can draw upon the set of rows that have previously been selected.

CTEs can also be applied to DML constructs UPDATE, INSERT and DELETE on some databases, both as a source of CTE rows when combined with RETURNING, as well as a consumer of CTE rows.

SQLAlchemy detects CTE objects, which are treated similarly to Alias objects, as special elements to be delivered to the FROM clause of the statement as well as to a WITH clause at the top of the statement.

For special prefixes such as PostgreSQL “MATERIALIZED” and “NOT MATERIALIZED”, the CTE.prefix_with() method may be used to establish these.

Changed in version 1.3.13: Added support for prefixes. In particular - MATERIALIZED and NOT MATERIALIZED.

Parameters:

name – name given to the common table expression. Like FromClause.alias(), the name can be left as None in which case an anonymous symbol will be used at query compile time.
recursive – if True, will render WITH RECURSIVE. A recursive common table expression is intended to be used in conjunction with UNION ALL in order to derive rows from those already selected.
nesting –
if True, will render the CTE locally to the statement in which it is referenced. For more complex scenarios, the HasCTE.add_cte() method using the HasCTE.add_cte.nest_here parameter may also be used to more carefully control the exact placement of a particular CTE.

New in version 1.4.24.

See also

HasCTE.add_cte()

The following examples include two from PostgreSQL’s documentation at https://www.postgresql.org/docs/current/static/queries-with.html, as well as additional examples.

Example 1, non recursive:

from sqlalchemy import (Table, Column, String, Integer,
                        MetaData, select, func)

metadata = MetaData()

orders = Table('orders', metadata,
    Column('region', String),
    Column('amount', Integer),
    Column('product', String),
    Column('quantity', Integer)
)

regional_sales = select(
                    orders.c.region,
                    func.sum(orders.c.amount).label('total_sales')
                ).group_by(orders.c.region).cte("regional_sales")


top_regions = select(regional_sales.c.region).\
        where(
            regional_sales.c.total_sales >
            select(
                func.sum(regional_sales.c.total_sales) / 10
            )
        ).cte("top_regions")

statement = select(
            orders.c.region,
            orders.c.product,
            func.sum(orders.c.quantity).label("product_units"),
            func.sum(orders.c.amount).label("product_sales")
    ).where(orders.c.region.in_(
        select(top_regions.c.region)
    )).group_by(orders.c.region, orders.c.product)

result = conn.execute(statement).fetchall()

Example 2, WITH RECURSIVE:

from sqlalchemy import (Table, Column, String, Integer,
                        MetaData, select, func)

metadata = MetaData()

parts = Table('parts', metadata,
    Column('part', String),
    Column('sub_part', String),
    Column('quantity', Integer),
)

included_parts = select(\
    parts.c.sub_part, parts.c.part, parts.c.quantity\
    ).\
    where(parts.c.part=='our part').\
    cte(recursive=True)


incl_alias = included_parts.alias()
parts_alias = parts.alias()
included_parts = included_parts.union_all(
    select(
        parts_alias.c.sub_part,
        parts_alias.c.part,
        parts_alias.c.quantity
    ).\
    where(parts_alias.c.part==incl_alias.c.sub_part)
)

statement = select(
            included_parts.c.sub_part,
            func.sum(included_parts.c.quantity).
              label('total_quantity')
        ).\
        group_by(included_parts.c.sub_part)

result = conn.execute(statement).fetchall()

Example 3, an upsert using UPDATE and INSERT with CTEs:

from datetime import date
from sqlalchemy import (MetaData, Table, Column, Integer,
                        Date, select, literal, and_, exists)

metadata = MetaData()

visitors = Table('visitors', metadata,
    Column('product_id', Integer, primary_key=True),
    Column('date', Date, primary_key=True),
    Column('count', Integer),
)

# add 5 visitors for the product_id == 1
product_id = 1
day = date.today()
count = 5

update_cte = (
    visitors.update()
    .where(and_(visitors.c.product_id == product_id,
                visitors.c.date == day))
    .values(count=visitors.c.count + count)
    .returning(literal(1))
    .cte('update_cte')
)

upsert = visitors.insert().from_select(
    [visitors.c.product_id, visitors.c.date, visitors.c.count],
    select(literal(product_id), literal(day), literal(count))
        .where(~exists(update_cte.select()))
)

connection.execute(upsert)

Example 4, Nesting CTE (SQLAlchemy 1.4.24 and above):

value_a = select(
    literal("root").label("n")
).cte("value_a")

# A nested CTE with the same name as the root one
value_a_nested = select(
    literal("nesting").label("n")
).cte("value_a", nesting=True)

# Nesting CTEs takes ascendency locally
# over the CTEs at a higher level
value_b = select(value_a_nested.c.n).cte("value_b")

value_ab = select(value_a.c.n.label("a"), value_b.c.n.label("b"))

The above query will render the second CTE nested inside the first, shown with inline parameters below as:

WITH
    value_a AS
        (SELECT 'root' AS n),
    value_b AS
        (WITH value_a AS
            (SELECT 'nesting' AS n)
        SELECT value_a.n AS n FROM value_a)
SELECT value_a.n AS a, value_b.n AS b
FROM value_a, value_b

The same CTE can be set up using the HasCTE.add_cte() method as follows (SQLAlchemy 2.0 and above):

value_a = select(
    literal("root").label("n")
).cte("value_a")

# A nested CTE with the same name as the root one
value_a_nested = select(
    literal("nesting").label("n")
).cte("value_a")

# Nesting CTEs takes ascendency locally
# over the CTEs at a higher level
value_b = (
    select(value_a_nested.c.n).
    add_cte(value_a_nested, nest_here=True).
    cte("value_b")
)

value_ab = select(value_a.c.n.label("a"), value_b.c.n.label("b"))

Example 5, Non-Linear CTE (SQLAlchemy 1.4.28 and above):

edge = Table(
    "edge",
    metadata,
    Column("id", Integer, primary_key=True),
    Column("left", Integer),
    Column("right", Integer),
)

root_node = select(literal(1).label("node")).cte(
    "nodes", recursive=True
)

left_edge = select(edge.c.left).join(
    root_node, edge.c.right == root_node.c.node
)
right_edge = select(edge.c.right).join(
    root_node, edge.c.left == root_node.c.node
)

subgraph_cte = root_node.union(left_edge, right_edge)

subgraph = select(subgraph_cte)

The above query will render 2 UNIONs inside the recursive CTE:

WITH RECURSIVE nodes(node) AS (
        SELECT 1 AS node
    UNION
        SELECT edge."left" AS "left"
        FROM edge JOIN nodes ON edge."right" = nodes.node
    UNION
        SELECT edge."right" AS "right"
        FROM edge JOIN nodes ON edge."left" = nodes.node
)
SELECT nodes.node FROM nodes

See also

Query.cte() - ORM version of HasCTE.cte().

method sqlalchemy.sql.expression.Select.distinct(*expr: _ColumnExpressionArgument[Any]) → Self¶

Return a new select() construct which will apply DISTINCT to its columns clause.

Parameters:

*expr –

optional column expressions. When present, the PostgreSQL dialect will render a DISTINCT ON (<expressions>>) construct.

Deprecated since version 1.4: Using *expr in other dialects is deprecated and will raise CompileError in a future version.

method sqlalchemy.sql.expression.Select.except_(*other: _SelectStatementForCompoundArgument) → CompoundSelect¶

Return a SQL EXCEPT of this select() construct against the given selectable provided as positional arguments.

Parameters:

*other –

one or more elements with which to create a UNION.

Changed in version 1.4.28: multiple elements are now accepted.

method sqlalchemy.sql.expression.Select.except_all(*other: _SelectStatementForCompoundArgument) → CompoundSelect¶

Return a SQL EXCEPT ALL of this select() construct against the given selectables provided as positional arguments.

Parameters:

*other –

one or more elements with which to create a UNION.

Changed in version 1.4.28: multiple elements are now accepted.

method sqlalchemy.sql.expression.Select.execution_options(**kw: Any) → Self¶

inherited from the Executable.execution_options() method of Executable

Set non-SQL options for the statement which take effect during execution.

Execution options can be set at many scopes, including per-statement, per-connection, or per execution, using methods such as Connection.execution_options() and parameters which accept a dictionary of options such as Connection.execute.execution_options and Session.execute.execution_options.

The primary characteristic of an execution option, as opposed to other kinds of options such as ORM loader options, is that execution options never affect the compiled SQL of a query, only things that affect how the SQL statement itself is invoked or how results are fetched. That is, execution options are not part of what’s accommodated by SQL compilation nor are they considered part of the cached state of a statement.

The Executable.execution_options() method is generative, as is the case for the method as applied to the Engine and Query objects, which means when the method is called, a copy of the object is returned, which applies the given parameters to that new copy, but leaves the original unchanged:

statement = select(table.c.x, table.c.y)
new_statement = statement.execution_options(my_option=True)

An exception to this behavior is the Connection object, where the Connection.execution_options() method is explicitly not generative.

The kinds of options that may be passed to Executable.execution_options() and other related methods and parameter dictionaries include parameters that are explicitly consumed by SQLAlchemy Core or ORM, as well as arbitrary keyword arguments not defined by SQLAlchemy, which means the methods and/or parameter dictionaries may be used for user-defined parameters that interact with custom code, which may access the parameters using methods such as Executable.get_execution_options() and Connection.get_execution_options(), or within selected event hooks using a dedicated execution_options event parameter such as ConnectionEvents.before_execute.execution_options or ORMExecuteState.execution_options, e.g.:

from sqlalchemy import event

@event.listens_for(some_engine, "before_execute")
def _process_opt(conn, statement, multiparams, params, execution_options):
    "run a SQL function before invoking a statement"

    if execution_options.get("do_special_thing", False):
        conn.exec_driver_sql("run_special_function()")

Within the scope of options that are explicitly recognized by SQLAlchemy, most apply to specific classes of objects and not others. The most common execution options include:

Connection.execution_options.isolation_level - sets the isolation level for a connection or a class of connections via an Engine. This option is accepted only by Connection or Engine.
Connection.execution_options.stream_results - indicates results should be fetched using a server side cursor; this option is accepted by Connection, by the Connection.execute.execution_options parameter on Connection.execute(), and additionally by Executable.execution_options() on a SQL statement object, as well as by ORM constructs like Session.execute().
Connection.execution_options.compiled_cache - indicates a dictionary that will serve as the SQL compilation cache for a Connection or Engine, as well as for ORM methods like Session.execute(). Can be passed as None to disable caching for statements. This option is not accepted by Executable.execution_options() as it is inadvisable to carry along a compilation cache within a statement object.
Connection.execution_options.schema_translate_map - a mapping of schema names used by the Schema Translate Map feature, accepted by Connection, Engine, Executable, as well as by ORM constructs like Session.execute().

See also

ORM Execution Options - documentation on all ORM-specific execution options

method sqlalchemy.sql.expression.Select.exists() → Exists¶

inherited from the SelectBase.exists() method of SelectBase

Return an Exists representation of this selectable, which can be used as a column expression.

The returned object is an instance of Exists.

See also

EXISTS subqueries - in the 2.0 style tutorial.

New in version 1.4.

attribute sqlalchemy.sql.expression.Select.exported_columns¶

inherited from the SelectBase.exported_columns attribute of SelectBase

A ColumnCollection that represents the “exported” columns of this Selectable, not including TextClause constructs.

The “exported” columns for a SelectBase object are synonymous with the SelectBase.selected_columns collection.

New in version 1.4.

See also

method sqlalchemy.sql.expression.Select.fetch(count: _LimitOffsetType, with_ties: bool = False, percent: bool = False) → Self¶

inherited from the GenerativeSelect.fetch() method of GenerativeSelect

Return a new selectable with the given FETCH FIRST criterion applied.

This is a numeric value which usually renders as FETCH {FIRST | NEXT} [ count ] {ROW | ROWS} {ONLY | WITH TIES} expression in the resulting select. This functionality is is currently implemented for Oracle, PostgreSQL, MSSQL.

Use GenerativeSelect.offset() to specify the offset.

Note

The GenerativeSelect.fetch() method will replace any clause applied with GenerativeSelect.limit().

New in version 1.4.

Parameters:

count – an integer COUNT parameter, or a SQL expression that provides an integer result. When percent=True this will represent the percentage of rows to return, not the absolute value. Pass None to reset it.
with_ties – When True, the WITH TIES option is used to return any additional rows that tie for the last place in the result set according to the ORDER BY clause. The ORDER BY may be mandatory in this case. Defaults to False
percent – When True, count represents the percentage of the total number of selected rows to return. Defaults to False

See also

Select.columns_clause_froms

method sqlalchemy.sql.expression.Select.filter(*criteria: _ColumnExpressionArgument[bool]) → Self¶: A synonym for the Select.where() method.

method sqlalchemy.sql.expression.Select.filter_by(**kwargs: Any) → Self¶: apply the given filtering criterion as a WHERE clause to this select.

method sqlalchemy.sql.expression.Select.from_statement(statement: ReturnsRowsRole) → ExecutableReturnsRows¶

Apply the columns which this Select would select onto another statement.

This operation is plugin-specific and will raise a not supported exception if this Select does not select from plugin-enabled entities.

The statement is typically either a text() or select() construct, and should return the set of columns appropriate to the entities represented by this Select.

See also

Getting ORM Results from Textual Statements - usage examples in the ORM Querying Guide

attribute sqlalchemy.sql.expression.Select.froms¶: Return the displayed list of FromClause elements.

Deprecated since version 1.4.23: The Select.froms attribute is moved to the Select.get_final_froms() method.

method sqlalchemy.sql.expression.Select.get_children(**kw: Any) → Iterable[ClauseElement]¶

Return immediate child HasTraverseInternals elements of this HasTraverseInternals.

This is used for visit traversal.

**kw may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

method sqlalchemy.sql.expression.Select.get_execution_options() → _ExecuteOptions¶: inherited from the Executable.get_execution_options() method of Executable

Get the non-SQL options which will take effect during execution.

New in version 1.3.

See also

Executable.execution_options()

method sqlalchemy.sql.expression.Select.get_final_froms() → Sequence[FromClause]¶

Compute the final displayed list of FromClause elements.

This method will run through the full computation required to determine what FROM elements will be displayed in the resulting SELECT statement, including shadowing individual tables with JOIN objects, as well as full computation for ORM use cases including eager loading clauses.

For ORM use, this accessor returns the post compilation list of FROM objects; this collection will include elements such as eagerly loaded tables and joins. The objects will not be ORM enabled and not work as a replacement for the Select.select_froms() collection; additionally, the method is not well performing for an ORM enabled statement as it will incur the full ORM construction process.

To retrieve the FROM list that’s implied by the “columns” collection passed to the Select originally, use the Select.columns_clause_froms accessor.

To select from an alternative set of columns while maintaining the FROM list, use the Select.with_only_columns() method and pass the Select.with_only_columns.maintain_column_froms parameter.

New in version 1.4.23: - the Select.get_final_froms() method replaces the previous Select.froms accessor, which is deprecated.

See also

method sqlalchemy.sql.expression.Select.get_label_style() → SelectLabelStyle¶: inherited from the GenerativeSelect.get_label_style() method of GenerativeSelect

Retrieve the current label style.

New in version 1.4.

method sqlalchemy.sql.expression.Select.group_by(_GenerativeSelect__first: Literal[None, _NoArg.NO_ARG] | _ColumnExpressionOrStrLabelArgument[Any] = _NoArg.NO_ARG, *clauses: _ColumnExpressionOrStrLabelArgument[Any]) → Self¶

inherited from the GenerativeSelect.group_by() method of GenerativeSelect

Return a new selectable with the given list of GROUP BY criterion applied.

All existing GROUP BY settings can be suppressed by passing None.

e.g.:

stmt = select(table.c.name, func.max(table.c.stat)).\
group_by(table.c.name)

Parameters:: *clauses – a series of ColumnElement constructs which will be used to generate an GROUP BY clause.

Ordering or Grouping by a Label - in the SQLAlchemy Unified Tutorial

method sqlalchemy.sql.expression.Select.having(*having: _ColumnExpressionArgument[bool]) → Self¶: Return a new select() construct with the given expression added to its HAVING clause, joined to the existing clause via AND, if any.

attribute sqlalchemy.sql.expression.Select.inherit_cache: bool | None = None¶

inherited from the HasCacheKey.inherit_cache attribute of HasCacheKey

Indicate if this HasCacheKey instance should make use of the cache key generation scheme used by its immediate superclass.

The attribute defaults to None, which indicates that a construct has not yet taken into account whether or not its appropriate for it to participate in caching; this is functionally equivalent to setting the value to False, except that a warning is also emitted.

This flag can be set to True on a particular class, if the SQL that corresponds to the object does not change based on attributes which are local to this class, and not its superclass.

See also

Enabling Caching Support for Custom Constructs - General guideslines for setting the HasCacheKey.inherit_cache attribute for third-party or user defined SQL constructs.

attribute sqlalchemy.sql.expression.Select.inner_columns¶

An iterator of all ColumnElement expressions which would be rendered into the columns clause of the resulting SELECT statement.

This method is legacy as of 1.4 and is superseded by the Select.exported_columns collection.

method sqlalchemy.sql.expression.Select.intersect(*other: _SelectStatementForCompoundArgument) → CompoundSelect¶

Return a SQL INTERSECT of this select() construct against the given selectables provided as positional arguments.

Parameters:

*other –
one or more elements with which to create a UNION.

Changed in version 1.4.28: multiple elements are now accepted.
**kwargs – keyword arguments are forwarded to the constructor for the newly created CompoundSelect object.

method sqlalchemy.sql.expression.Select.intersect_all(*other: _SelectStatementForCompoundArgument) → CompoundSelect¶

Return a SQL INTERSECT ALL of this select() construct against the given selectables provided as positional arguments.

Parameters:

*other –
one or more elements with which to create a UNION.

Changed in version 1.4.28: multiple elements are now accepted.
**kwargs – keyword arguments are forwarded to the constructor for the newly created CompoundSelect object.

method sqlalchemy.sql.expression.Select.is_derived_from(fromclause: FromClause | None) → bool¶

Return True if this ReturnsRows is ‘derived’ from the given FromClause.

An example would be an Alias of a Table is derived from that Table.

method sqlalchemy.sql.expression.Select.join(target: _JoinTargetArgument, onclause: _OnClauseArgument | None = None, *, isouter: bool = False, full: bool = False) → Self¶

Create a SQL JOIN against this Select object’s criterion and apply generatively, returning the newly resulting Select.

E.g.:

stmt = select(user_table).join(address_table, user_table.c.id == address_table.c.user_id)

The above statement generates SQL similar to:

SELECT user.id, user.name FROM user JOIN address ON user.id = address.user_id

Changed in version 1.4: Select.join() now creates a Join object between a FromClause source that is within the FROM clause of the existing SELECT, and a given target FromClause, and then adds this Join to the FROM clause of the newly generated SELECT statement. This is completely reworked from the behavior in 1.3, which would instead create a subquery of the entire Select and then join that subquery to the target.

This is a backwards incompatible change as the previous behavior was mostly useless, producing an unnamed subquery rejected by most databases in any case. The new behavior is modeled after that of the very successful Query.join() method in the ORM, in order to support the functionality of Query being available by using a Select object with an Session.

See the notes for this change at select().join() and outerjoin() add JOIN criteria to the current query, rather than creating a subquery.

Parameters:

target – target table to join towards
onclause – ON clause of the join. If omitted, an ON clause is generated automatically based on the ForeignKey linkages between the two tables, if one can be unambiguously determined, otherwise an error is raised.
isouter – if True, generate LEFT OUTER join. Same as Select.outerjoin().
full – if True, generate FULL OUTER join.

Joins - in the ORM Querying Guide

Select.join_from()

Select.outerjoin()

method sqlalchemy.sql.expression.Select.join_from(from_: _FromClauseArgument, target: _JoinTargetArgument, onclause: _OnClauseArgument | None = None, *, isouter: bool = False, full: bool = False) → Self¶

Create a SQL JOIN against this Select object’s criterion and apply generatively, returning the newly resulting Select.

E.g.:

stmt = select(user_table, address_table).join_from(
    user_table, address_table, user_table.c.id == address_table.c.user_id
)

The above statement generates SQL similar to:

SELECT user.id, user.name, address.id, address.email, address.user_id
FROM user JOIN address ON user.id = address.user_id

New in version 1.4.

Parameters:

from_ – the left side of the join, will be rendered in the FROM clause and is roughly equivalent to using the Select.select_from() method.
target – target table to join towards
onclause – ON clause of the join.
isouter – if True, generate LEFT OUTER join. Same as Select.outerjoin().
full – if True, generate FULL OUTER join.

Joins - in the ORM Querying Guide

Select.join()

method sqlalchemy.sql.expression.Select.label(name: str | None) → Label[Any]¶: inherited from the SelectBase.label() method of SelectBase

Return a ‘scalar’ representation of this selectable, embedded as a subquery with a label.

See also

SelectBase.scalar_subquery().

method sqlalchemy.sql.expression.Select.lateral(name: str | None = None) → LateralFromClause¶

inherited from the SelectBase.lateral() method of SelectBase

Return a LATERAL alias of this Selectable.

The return value is the Lateral construct also provided by the top-level lateral() function.

See also

LATERAL correlation - overview of usage.

method sqlalchemy.sql.expression.Select.limit(limit: _LimitOffsetType) → Self¶

inherited from the GenerativeSelect.limit() method of GenerativeSelect

Return a new selectable with the given LIMIT criterion applied.

This is a numerical value which usually renders as a LIMIT expression in the resulting select. Backends that don’t support LIMIT will attempt to provide similar functionality.

Note

The GenerativeSelect.limit() method will replace any clause applied with GenerativeSelect.fetch().

Parameters:: limit – an integer LIMIT parameter, or a SQL expression that provides an integer result. Pass None to reset it.

See also

method sqlalchemy.sql.expression.Select.offset(offset: _LimitOffsetType) → Self¶

inherited from the GenerativeSelect.offset() method of GenerativeSelect

Return a new selectable with the given OFFSET criterion applied.

This is a numeric value which usually renders as an OFFSET expression in the resulting select. Backends that don’t support OFFSET will attempt to provide similar functionality.

Parameters:: offset – an integer OFFSET parameter, or a SQL expression that provides an integer result. Pass None to reset it.

See also

method sqlalchemy.sql.expression.Select.options(*options: ExecutableOption) → Self¶

inherited from the Executable.options() method of Executable

Apply options to this statement.

In the general sense, options are any kind of Python object that can be interpreted by the SQL compiler for the statement. These options can be consumed by specific dialects or specific kinds of compilers.

The most commonly known kind of option are the ORM level options that apply “eager load” and other loading behaviors to an ORM query. However, options can theoretically be used for many other purposes.

For background on specific kinds of options for specific kinds of statements, refer to the documentation for those option objects.

Changed in version 1.4: - added Executable.options() to Core statement objects towards the goal of allowing unified Core / ORM querying capabilities.

See also

Column Loading Options - refers to options specific to the usage of ORM queries

Relationship Loading with Loader Options - refers to options specific to the usage of ORM queries

method sqlalchemy.sql.expression.Select.order_by(_GenerativeSelect__first: Literal[None, _NoArg.NO_ARG] | _ColumnExpressionOrStrLabelArgument[Any] = _NoArg.NO_ARG, *clauses: _ColumnExpressionOrStrLabelArgument[Any]) → Self¶

inherited from the GenerativeSelect.order_by() method of GenerativeSelect

Return a new selectable with the given list of ORDER BY criteria applied.

e.g.:

stmt = select(table).order_by(table.c.id, table.c.name)

Calling this method multiple times is equivalent to calling it once with all the clauses concatenated. All existing ORDER BY criteria may be cancelled by passing None by itself. New ORDER BY criteria may then be added by invoking Query.order_by() again, e.g.:

# will erase all ORDER BY and ORDER BY new_col alone
stmt = stmt.order_by(None).order_by(new_col)

Parameters:: *clauses – a series of ColumnElement constructs which will be used to generate an ORDER BY clause.

Ordering or Grouping by a Label - in the SQLAlchemy Unified Tutorial

method sqlalchemy.sql.expression.Select.outerjoin(target: _JoinTargetArgument, onclause: _OnClauseArgument | None = None, *, full: bool = False) → Self¶

Create a left outer join.

Parameters are the same as that of Select.join().

Changed in version 1.4: Select.outerjoin() now creates a Join object between a FromClause source that is within the FROM clause of the existing SELECT, and a given target FromClause, and then adds this Join to the FROM clause of the newly generated SELECT statement. This is completely reworked from the behavior in 1.3, which would instead create a subquery of the entire Select and then join that subquery to the target.

This is a backwards incompatible change as the previous behavior was mostly useless, producing an unnamed subquery rejected by most databases in any case. The new behavior is modeled after that of the very successful Query.join() method in the ORM, in order to support the functionality of Query being available by using a Select object with an Session.

See the notes for this change at select().join() and outerjoin() add JOIN criteria to the current query, rather than creating a subquery.

Joins - in the ORM Querying Guide

Select.join()

method sqlalchemy.sql.expression.Select.outerjoin_from(from_: _FromClauseArgument, target: _JoinTargetArgument, onclause: _OnClauseArgument | None = None, *, full: bool = False) → Self¶

Create a SQL LEFT OUTER JOIN against this Select object’s criterion and apply generatively, returning the newly resulting Select.

Usage is the same as that of Select.join_from().

method sqlalchemy.sql.expression.Select.prefix_with(*prefixes: _TextCoercedExpressionArgument[Any], dialect: str = '*') → Self¶

inherited from the HasPrefixes.prefix_with() method of HasPrefixes

Add one or more expressions following the statement keyword, i.e. SELECT, INSERT, UPDATE, or DELETE. Generative.

This is used to support backend-specific prefix keywords such as those provided by MySQL.

E.g.:

stmt = table.insert().prefix_with("LOW_PRIORITY", dialect="mysql")

# MySQL 5.7 optimizer hints
stmt = select(table).prefix_with(
    "/*+ BKA(t1) */", dialect="mysql")

Multiple prefixes can be specified by multiple calls to HasPrefixes.prefix_with().

Parameters:

*prefixes – textual or ClauseElement construct which will be rendered following the INSERT, UPDATE, or DELETE keyword.
dialect – optional string dialect name which will limit rendering of this prefix to only that dialect.

method sqlalchemy.sql.expression.Select.reduce_columns(only_synonyms: bool = True) → Select¶

Return a new select() construct with redundantly named, equivalently-valued columns removed from the columns clause.

“Redundant” here means two columns where one refers to the other either based on foreign key, or via a simple equality comparison in the WHERE clause of the statement. The primary purpose of this method is to automatically construct a select statement with all uniquely-named columns, without the need to use table-qualified labels as Select.set_label_style() does.

When columns are omitted based on foreign key, the referred-to column is the one that’s kept. When columns are omitted based on WHERE equivalence, the first column in the columns clause is the one that’s kept.

Parameters:: only_synonyms – when True, limit the removal of columns to those which have the same name as the equivalent. Otherwise, all columns that are equivalent to another are removed.

method sqlalchemy.sql.expression.Select.replace_selectable(old: FromClause, alias: Alias) → Self¶: inherited from the Selectable.replace_selectable() method of Selectable

Replace all occurrences of FromClause ‘old’ with the given Alias object, returning a copy of this FromClause.

Deprecated since version 1.4: The Selectable.replace_selectable() method is deprecated, and will be removed in a future release. Similar functionality is available via the sqlalchemy.sql.visitors module.

method sqlalchemy.sql.expression.Select.scalar_subquery() → ScalarSelect[Any]¶

inherited from the SelectBase.scalar_subquery() method of SelectBase

Return a ‘scalar’ representation of this selectable, which can be used as a column expression.

The returned object is an instance of ScalarSelect.

Typically, a select statement which has only one column in its columns clause is eligible to be used as a scalar expression. The scalar subquery can then be used in the WHERE clause or columns clause of an enclosing SELECT.

Note that the scalar subquery differentiates from the FROM-level subquery that can be produced using the SelectBase.subquery() method.

See also

Scalar and Correlated Subqueries - in the 2.0 tutorial

method sqlalchemy.sql.expression.Select.select(*arg: Any, **kw: Any) → Select¶: inherited from the SelectBase.select() method of SelectBase

Deprecated since version 1.4: The SelectBase.select() method is deprecated and will be removed in a future release; this method implicitly creates a subquery that should be explicit. Please call SelectBase.subquery() first in order to create a subquery, which then can be selected.

method sqlalchemy.sql.expression.Select.select_from(*froms: _FromClauseArgument) → Self¶

Return a new select() construct with the given FROM expression(s) merged into its list of FROM objects.

E.g.:

table1 = table('t1', column('a'))
table2 = table('t2', column('b'))
s = select(table1.c.a).\
    select_from(
        table1.join(table2, table1.c.a==table2.c.b)
    )

The “from” list is a unique set on the identity of each element, so adding an already present Table or other selectable will have no effect. Passing a Join that refers to an already present Table or other selectable will have the effect of concealing the presence of that selectable as an individual element in the rendered FROM list, instead rendering it into a JOIN clause.

While the typical purpose of Select.select_from() is to replace the default, derived FROM clause with a join, it can also be called with individual table elements, multiple times if desired, in the case that the FROM clause cannot be fully derived from the columns clause:

select(func.count('*')).select_from(table1)

attribute sqlalchemy.sql.expression.Select.selected_columns¶

A ColumnCollection representing the columns that this SELECT statement or similar construct returns in its result set, not including TextClause constructs.

This collection differs from the FromClause.columns collection of a FromClause in that the columns within this collection cannot be directly nested inside another SELECT statement; a subquery must be applied first which provides for the necessary parenthesization required by SQL.

For a select() construct, the collection here is exactly what would be rendered inside the “SELECT” statement, and the ColumnElement objects are directly present as they were given, e.g.:

col1 = column('q', Integer)
col2 = column('p', Integer)
stmt = select(col1, col2)

Above, stmt.selected_columns would be a collection that contains the col1 and col2 objects directly. For a statement that is against a Table or other FromClause, the collection will use the ColumnElement objects that are in the FromClause.c collection of the from element.

A use case for the Select.selected_columns collection is to allow the existing columns to be referenced when adding additional criteria, e.g.:

def filter_on_id(my_select, id):
    return my_select.where(my_select.selected_columns['id'] == id)

stmt = select(MyModel)

# adds "WHERE id=:param" to the statement
stmt = filter_on_id(stmt, 42)

Note

The Select.selected_columns collection does not include expressions established in the columns clause using the text() construct; these are silently omitted from the collection. To use plain textual column expressions inside of a Select construct, use the literal_column() construct.

New in version 1.4.

method sqlalchemy.sql.expression.Select.self_group(against: OperatorType | None = None) → SelectStatementGrouping | Self¶

Apply a ‘grouping’ to this ClauseElement.

This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by select() constructs when placed into the FROM clause of another select(). (Note that subqueries should be normally created using the Select.alias() method, as many platforms require nested SELECT statements to be named).

As expressions are composed together, the application of self_group() is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like x OR (y AND z) - AND takes precedence over OR.

The base self_group() method of ClauseElement just returns self.

method sqlalchemy.sql.expression.Select.set_label_style(style: SelectLabelStyle) → Self¶

inherited from the GenerativeSelect.set_label_style() method of GenerativeSelect

Return a new selectable with the specified label style.

There are three “label styles” available, SelectLabelStyle.LABEL_STYLE_DISAMBIGUATE_ONLY, SelectLabelStyle.LABEL_STYLE_TABLENAME_PLUS_COL, and SelectLabelStyle.LABEL_STYLE_NONE. The default style is SelectLabelStyle.LABEL_STYLE_TABLENAME_PLUS_COL.

In modern SQLAlchemy, there is not generally a need to change the labeling style, as per-expression labels are more effectively used by making use of the ColumnElement.label() method. In past versions, LABEL_STYLE_TABLENAME_PLUS_COL was used to disambiguate same-named columns from different tables, aliases, or subqueries; the newer LABEL_STYLE_DISAMBIGUATE_ONLY now applies labels only to names that conflict with an existing name so that the impact of this labeling is minimal.

The rationale for disambiguation is mostly so that all column expressions are available from a given FromClause.c collection when a subquery is created.

New in version 1.4: - the GenerativeSelect.set_label_style() method replaces the previous combination of .apply_labels(), .with_labels() and use_labels=True methods and/or parameters.

See also

LABEL_STYLE_DISAMBIGUATE_ONLY

LABEL_STYLE_TABLENAME_PLUS_COL

LABEL_STYLE_NONE

LABEL_STYLE_DEFAULT

method sqlalchemy.sql.expression.Select.slice(start: int, stop: int) → Self¶

inherited from the GenerativeSelect.slice() method of GenerativeSelect

Apply LIMIT / OFFSET to this statement based on a slice.

The start and stop indices behave like the argument to Python’s built-in range() function. This method provides an alternative to using LIMIT/OFFSET to get a slice of the query.

For example,

stmt = select(User).order_by(User).id.slice(1, 3)

renders as

SELECT users.id AS users_id,
       users.name AS users_name
FROM users ORDER BY users.id
LIMIT ? OFFSET ?
(2, 1)

Note

The GenerativeSelect.slice() method will replace any clause applied with GenerativeSelect.fetch().

New in version 1.4: Added the GenerativeSelect.slice() method generalized from the ORM.

See also

Select.with_statement_hint()

method sqlalchemy.sql.expression.Select.subquery(name: str | None = None) → Subquery¶

inherited from the SelectBase.subquery() method of SelectBase

Return a subquery of this SelectBase.

A subquery is from a SQL perspective a parenthesized, named construct that can be placed in the FROM clause of another SELECT statement.

Given a SELECT statement such as:

stmt = select(table.c.id, table.c.name)

The above statement might look like:

SELECT table.id, table.name FROM table

The subquery form by itself renders the same way, however when embedded into the FROM clause of another SELECT statement, it becomes a named sub-element:

subq = stmt.subquery()
new_stmt = select(subq)

The above renders as:

SELECT anon_1.id, anon_1.name
FROM (SELECT table.id, table.name FROM table) AS anon_1

Historically, SelectBase.subquery() is equivalent to calling the FromClause.alias() method on a FROM object; however, as a SelectBase object is not directly FROM object, the SelectBase.subquery() method provides clearer semantics.

New in version 1.4.

method sqlalchemy.sql.expression.Select.suffix_with(*suffixes: _TextCoercedExpressionArgument[Any], dialect: str = '*') → Self¶

inherited from the HasSuffixes.suffix_with() method of HasSuffixes

Add one or more expressions following the statement as a whole.

This is used to support backend-specific suffix keywords on certain constructs.

E.g.:

stmt = select(col1, col2).cte().suffix_with(
    "cycle empno set y_cycle to 1 default 0", dialect="oracle")

Multiple suffixes can be specified by multiple calls to HasSuffixes.suffix_with().

Parameters:

*suffixes – textual or ClauseElement construct which will be rendered following the target clause.
dialect – Optional string dialect name which will limit rendering of this suffix to only that dialect.

method sqlalchemy.sql.expression.Select.union(*other: _SelectStatementForCompoundArgument) → CompoundSelect¶

Return a SQL UNION of this select() construct against the given selectables provided as positional arguments.

Parameters:

*other –
one or more elements with which to create a UNION.

Changed in version 1.4.28: multiple elements are now accepted.
**kwargs – keyword arguments are forwarded to the constructor for the newly created CompoundSelect object.

method sqlalchemy.sql.expression.Select.union_all(*other: _SelectStatementForCompoundArgument) → CompoundSelect¶

Return a SQL UNION ALL of this select() construct against the given selectables provided as positional arguments.

Parameters:

*other –
one or more elements with which to create a UNION.

Changed in version 1.4.28: multiple elements are now accepted.
**kwargs – keyword arguments are forwarded to the constructor for the newly created CompoundSelect object.

method sqlalchemy.sql.expression.Select.where(*whereclause: _ColumnExpressionArgument[bool]) → Self¶: Return a new select() construct with the given expression added to its WHERE clause, joined to the existing clause via AND, if any.

attribute sqlalchemy.sql.expression.Select.whereclause¶

Return the completed WHERE clause for this Select statement.

This assembles the current collection of WHERE criteria into a single BooleanClauseList construct.

New in version 1.4.

method sqlalchemy.sql.expression.Select.with_for_update(*, nowait: bool = False, read: bool = False, of: _ForUpdateOfArgument | None = None, skip_locked: bool = False, key_share: bool = False) → Self¶

inherited from the GenerativeSelect.with_for_update() method of GenerativeSelect

Specify a FOR UPDATE clause for this GenerativeSelect.

E.g.:

stmt = select(table).with_for_update(nowait=True)

On a database like PostgreSQL or Oracle, the above would render a statement like:

SELECT table.a, table.b FROM table FOR UPDATE NOWAIT

on other backends, the nowait option is ignored and instead would produce:

SELECT table.a, table.b FROM table FOR UPDATE

When called with no arguments, the statement will render with the suffix FOR UPDATE. Additional arguments can then be provided which allow for common database-specific variants.

Parameters:

nowait – boolean; will render FOR UPDATE NOWAIT on Oracle and PostgreSQL dialects.
read – boolean; will render LOCK IN SHARE MODE on MySQL, FOR SHARE on PostgreSQL. On PostgreSQL, when combined with nowait, will render FOR SHARE NOWAIT.
of – SQL expression or list of SQL expression elements, (typically Column objects or a compatible expression, for some backends may also be a table expression) which will render into a FOR UPDATE OF clause; supported by PostgreSQL, Oracle, some MySQL versions and possibly others. May render as a table or as a column depending on backend.
skip_locked – boolean, will render FOR UPDATE SKIP LOCKED on Oracle and PostgreSQL dialects or FOR SHARE SKIP LOCKED if read=True is also specified.
key_share – boolean, will render FOR NO KEY UPDATE, or if combined with read=True will render FOR KEY SHARE, on the PostgreSQL dialect.

method sqlalchemy.sql.expression.Select.with_hint(selectable: _FromClauseArgument, text: str, dialect_name: str = '*') → Self¶

inherited from the HasHints.with_hint() method of HasHints

Add an indexing or other executional context hint for the given selectable to this Select or other selectable object.

The text of the hint is rendered in the appropriate location for the database backend in use, relative to the given Table or Alias passed as the selectable argument. The dialect implementation typically uses Python string substitution syntax with the token %(name)s to render the name of the table or alias. E.g. when using Oracle, the following:

select(mytable).\
    with_hint(mytable, "index(%(name)s ix_mytable)")

Would render SQL as:

select /*+ index(mytable ix_mytable) */ ... from mytable

The dialect_name option will limit the rendering of a particular hint to a particular backend. Such as, to add hints for both Oracle and Sybase simultaneously:

select(mytable).\
    with_hint(mytable, "index(%(name)s ix_mytable)", 'oracle').\
    with_hint(mytable, "WITH INDEX ix_mytable", 'mssql')

See also

method sqlalchemy.sql.expression.Select.with_only_columns(*entities: _ColumnsClauseArgument[Any], maintain_column_froms: bool = False, **_Select__kw: Any) → Select[Any]¶

Return a new select() construct with its columns clause replaced with the given entities.

By default, this method is exactly equivalent to as if the original select() had been called with the given entities. E.g. a statement:

s = select(table1.c.a, table1.c.b)
s = s.with_only_columns(table1.c.b)

should be exactly equivalent to:

s = select(table1.c.b)

In this mode of operation, Select.with_only_columns() will also dynamically alter the FROM clause of the statement if it is not explicitly stated. To maintain the existing set of FROMs including those implied by the current columns clause, add the Select.with_only_columns.maintain_column_froms parameter:

s = select(table1.c.a, table2.c.b)
s = s.with_only_columns(table1.c.a, maintain_column_froms=True)

The above parameter performs a transfer of the effective FROMs in the columns collection to the Select.select_from() method, as though the following were invoked:

s = select(table1.c.a, table2.c.b)
s = s.select_from(table1, table2).with_only_columns(table1.c.a)

The Select.with_only_columns.maintain_column_froms parameter makes use of the Select.columns_clause_froms collection and performs an operation equivalent to the following:

s = select(table1.c.a, table2.c.b)
s = s.select_from(*s.columns_clause_froms).with_only_columns(table1.c.a)

Parameters:

*entities – column expressions to be used.
maintain_column_froms –
boolean parameter that will ensure the FROM list implied from the current columns clause will be transferred to the Select.select_from() method first.

New in version 1.4.23.

method sqlalchemy.sql.expression.Select.with_statement_hint(text: str, dialect_name: str = '*') → Self¶

inherited from the HasHints.with_statement_hint() method of HasHints

Add a statement hint to this Select or other selectable object.

This method is similar to Select.with_hint() except that it does not require an individual table, and instead applies to the statement as a whole.

Hints here are specific to the backend database and may include directives such as isolation levels, file directives, fetch directives, etc.

See also

Select.with_hint()

Select.prefix_with() - generic SELECT prefixing which also can suit some database-specific HINT syntaxes such as MySQL optimizer hints

class sqlalchemy.sql.expression.Selectable¶

Mark a class as being selectable.

Members

corresponding_column(), exported_columns, inherit_cache, is_derived_from(), lateral(), replace_selectable()

Class signature

class sqlalchemy.sql.expression.Selectable (sqlalchemy.sql.expression.ReturnsRows)

method sqlalchemy.sql.expression.Selectable.corresponding_column(column: KeyedColumnElement[Any], require_embedded: bool = False) → KeyedColumnElement[Any] | None¶

Given a ColumnElement, return the exported ColumnElement object from the Selectable.exported_columns collection of this Selectable which corresponds to that original ColumnElement via a common ancestor column.

Parameters:

column – the target ColumnElement to be matched.
require_embedded – only return corresponding columns for the given ColumnElement, if the given ColumnElement is actually present within a sub-element of this Selectable. Normally the column will match if it merely shares a common ancestor with one of the exported columns of this Selectable.

See also

Selectable.exported_columns - the ColumnCollection that is used for the operation.

ColumnCollection.corresponding_column() - implementation method.

attribute sqlalchemy.sql.expression.Selectable.exported_columns¶

inherited from the ReturnsRows.exported_columns attribute of ReturnsRows

A ColumnCollection that represents the “exported” columns of this ReturnsRows.

The “exported” columns represent the collection of ColumnElement expressions that are rendered by this SQL construct. There are primary varieties which are the “FROM clause columns” of a FROM clause, such as a table, join, or subquery, the “SELECTed columns”, which are the columns in the “columns clause” of a SELECT statement, and the RETURNING columns in a DML statement..

New in version 1.4.

See also

attribute sqlalchemy.sql.expression.Selectable.inherit_cache: bool | None = None¶

inherited from the HasCacheKey.inherit_cache attribute of HasCacheKey

Indicate if this HasCacheKey instance should make use of the cache key generation scheme used by its immediate superclass.

The attribute defaults to None, which indicates that a construct has not yet taken into account whether or not its appropriate for it to participate in caching; this is functionally equivalent to setting the value to False, except that a warning is also emitted.

This flag can be set to True on a particular class, if the SQL that corresponds to the object does not change based on attributes which are local to this class, and not its superclass.

See also

Enabling Caching Support for Custom Constructs - General guideslines for setting the HasCacheKey.inherit_cache attribute for third-party or user defined SQL constructs.

method sqlalchemy.sql.expression.Selectable.is_derived_from(fromclause: FromClause | None) → bool¶

inherited from the ReturnsRows.is_derived_from() method of ReturnsRows

Return True if this ReturnsRows is ‘derived’ from the given FromClause.

An example would be an Alias of a Table is derived from that Table.

method sqlalchemy.sql.expression.Selectable.lateral(name: str | None = None) → LateralFromClause¶

Return a LATERAL alias of this Selectable.

The return value is the Lateral construct also provided by the top-level lateral() function.

See also

LATERAL correlation - overview of usage.

method sqlalchemy.sql.expression.Selectable.replace_selectable(old: FromClause, alias: Alias) → Self¶: Replace all occurrences of FromClause ‘old’ with the given Alias object, returning a copy of this FromClause.

Deprecated since version 1.4: The Selectable.replace_selectable() method is deprecated, and will be removed in a future release. Similar functionality is available via the sqlalchemy.sql.visitors module.

class sqlalchemy.sql.expression.SelectBase¶

Base class for SELECT statements.

This includes Select, CompoundSelect and TextualSelect.

Members

add_cte(), alias(), as_scalar(), c, corresponding_column(), cte(), exists(), exported_columns, get_label_style(), inherit_cache, is_derived_from(), label(), lateral(), replace_selectable(), scalar_subquery(), select(), selected_columns, set_label_style(), subquery()

Class signature

class sqlalchemy.sql.expression.SelectBase (sqlalchemy.sql.roles.SelectStatementRole, sqlalchemy.sql.roles.DMLSelectRole, sqlalchemy.sql.roles.CompoundElementRole, sqlalchemy.sql.roles.InElementRole, sqlalchemy.sql.expression.HasCTE, sqlalchemy.sql.annotation.SupportsCloneAnnotations, sqlalchemy.sql.expression.Selectable)

method sqlalchemy.sql.expression.SelectBase.add_cte(*ctes: CTE, nest_here: bool = False) → Self¶

inherited from the HasCTE.add_cte() method of HasCTE

Add one or more CTE constructs to this statement.

This method will associate the given CTE constructs with the parent statement such that they will each be unconditionally rendered in the WITH clause of the final statement, even if not referenced elsewhere within the statement or any sub-selects.

The optional HasCTE.add_cte.nest_here parameter when set to True will have the effect that each given CTE will render in a WITH clause rendered directly along with this statement, rather than being moved to the top of the ultimate rendered statement, even if this statement is rendered as a subquery within a larger statement.

This method has two general uses. One is to embed CTE statements that serve some purpose without being referenced explicitly, such as the use case of embedding a DML statement such as an INSERT or UPDATE as a CTE inline with a primary statement that may draw from its results indirectly. The other is to provide control over the exact placement of a particular series of CTE constructs that should remain rendered directly in terms of a particular statement that may be nested in a larger statement.

E.g.:

from sqlalchemy import table, column, select
t = table('t', column('c1'), column('c2'))

ins = t.insert().values({"c1": "x", "c2": "y"}).cte()

stmt = select(t).add_cte(ins)

Would render:

WITH anon_1 AS
(INSERT INTO t (c1, c2) VALUES (:param_1, :param_2))
SELECT t.c1, t.c2
FROM t

Above, the “anon_1” CTE is not referenced in the SELECT statement, however still accomplishes the task of running an INSERT statement.

Similarly in a DML-related context, using the PostgreSQL Insert construct to generate an “upsert”:

from sqlalchemy import table, column
from sqlalchemy.dialects.postgresql import insert

t = table("t", column("c1"), column("c2"))

delete_statement_cte = (
    t.delete().where(t.c.c1 < 1).cte("deletions")
)

insert_stmt = insert(t).values({"c1": 1, "c2": 2})
update_statement = insert_stmt.on_conflict_do_update(
    index_elements=[t.c.c1],
    set_={
        "c1": insert_stmt.excluded.c1,
        "c2": insert_stmt.excluded.c2,
    },
).add_cte(delete_statement_cte)

print(update_statement)

The above statement renders as:

WITH deletions AS
(DELETE FROM t WHERE t.c1 < %(c1_1)s)
INSERT INTO t (c1, c2) VALUES (%(c1)s, %(c2)s)
ON CONFLICT (c1) DO UPDATE SET c1 = excluded.c1, c2 = excluded.c2

New in version 1.4.21.

Parameters:

*ctes –
zero or more CTE constructs.

Changed in version 2.0: Multiple CTE instances are accepted
nest_here –
if True, the given CTE or CTEs will be rendered as though they specified the HasCTE.cte.nesting flag to True when they were added to this HasCTE. Assuming the given CTEs are not referenced in an outer-enclosing statement as well, the CTEs given should render at the level of this statement when this flag is given.

New in version 2.0.

See also

HasCTE.cte.nesting

method sqlalchemy.sql.expression.SelectBase.alias(name: str | None = None, flat: bool = False) → Subquery¶

Return a named subquery against this SelectBase.

For a SelectBase (as opposed to a FromClause), this returns a Subquery object which behaves mostly the same as the Alias object that is used with a FromClause.

Changed in version 1.4: The SelectBase.alias() method is now a synonym for the SelectBase.subquery() method.

method sqlalchemy.sql.expression.SelectBase.as_scalar() → ScalarSelect[Any]¶: Deprecated since version 1.4: The SelectBase.as_scalar() method is deprecated and will be removed in a future release. Please refer to SelectBase.scalar_subquery().

attribute sqlalchemy.sql.expression.SelectBase.c¶: Deprecated since version 1.4: The SelectBase.c and SelectBase.columns attributes are deprecated and will be removed in a future release; these attributes implicitly create a subquery that should be explicit. Please call SelectBase.subquery() first in order to create a subquery, which then contains this attribute. To access the columns that this SELECT object SELECTs from, use the SelectBase.selected_columns attribute.

method sqlalchemy.sql.expression.SelectBase.corresponding_column(column: KeyedColumnElement[Any], require_embedded: bool = False) → KeyedColumnElement[Any] | None¶

inherited from the Selectable.corresponding_column() method of Selectable

Given a ColumnElement, return the exported ColumnElement object from the Selectable.exported_columns collection of this Selectable which corresponds to that original ColumnElement via a common ancestor column.

Parameters:

column – the target ColumnElement to be matched.
require_embedded – only return corresponding columns for the given ColumnElement, if the given ColumnElement is actually present within a sub-element of this Selectable. Normally the column will match if it merely shares a common ancestor with one of the exported columns of this Selectable.

See also

Selectable.exported_columns - the ColumnCollection that is used for the operation.

ColumnCollection.corresponding_column() - implementation method.

method sqlalchemy.sql.expression.SelectBase.cte(name: str | None = None, recursive: bool = False, nesting: bool = False) → CTE¶

inherited from the HasCTE.cte() method of HasCTE

Return a new CTE, or Common Table Expression instance.

Common table expressions are a SQL standard whereby SELECT statements can draw upon secondary statements specified along with the primary statement, using a clause called “WITH”. Special semantics regarding UNION can also be employed to allow “recursive” queries, where a SELECT statement can draw upon the set of rows that have previously been selected.

CTEs can also be applied to DML constructs UPDATE, INSERT and DELETE on some databases, both as a source of CTE rows when combined with RETURNING, as well as a consumer of CTE rows.

SQLAlchemy detects CTE objects, which are treated similarly to Alias objects, as special elements to be delivered to the FROM clause of the statement as well as to a WITH clause at the top of the statement.

For special prefixes such as PostgreSQL “MATERIALIZED” and “NOT MATERIALIZED”, the CTE.prefix_with() method may be used to establish these.

Changed in version 1.3.13: Added support for prefixes. In particular - MATERIALIZED and NOT MATERIALIZED.

Parameters:

name – name given to the common table expression. Like FromClause.alias(), the name can be left as None in which case an anonymous symbol will be used at query compile time.
recursive – if True, will render WITH RECURSIVE. A recursive common table expression is intended to be used in conjunction with UNION ALL in order to derive rows from those already selected.
nesting –
if True, will render the CTE locally to the statement in which it is referenced. For more complex scenarios, the HasCTE.add_cte() method using the HasCTE.add_cte.nest_here parameter may also be used to more carefully control the exact placement of a particular CTE.

New in version 1.4.24.

See also

HasCTE.add_cte()

The following examples include two from PostgreSQL’s documentation at https://www.postgresql.org/docs/current/static/queries-with.html, as well as additional examples.

Example 1, non recursive:

from sqlalchemy import (Table, Column, String, Integer,
                        MetaData, select, func)

metadata = MetaData()

orders = Table('orders', metadata,
    Column('region', String),
    Column('amount', Integer),
    Column('product', String),
    Column('quantity', Integer)
)

regional_sales = select(
                    orders.c.region,
                    func.sum(orders.c.amount).label('total_sales')
                ).group_by(orders.c.region).cte("regional_sales")


top_regions = select(regional_sales.c.region).\
        where(
            regional_sales.c.total_sales >
            select(
                func.sum(regional_sales.c.total_sales) / 10
            )
        ).cte("top_regions")

statement = select(
            orders.c.region,
            orders.c.product,
            func.sum(orders.c.quantity).label("product_units"),
            func.sum(orders.c.amount).label("product_sales")
    ).where(orders.c.region.in_(
        select(top_regions.c.region)
    )).group_by(orders.c.region, orders.c.product)

result = conn.execute(statement).fetchall()

Example 2, WITH RECURSIVE:

from sqlalchemy import (Table, Column, String, Integer,
                        MetaData, select, func)

metadata = MetaData()

parts = Table('parts', metadata,
    Column('part', String),
    Column('sub_part', String),
    Column('quantity', Integer),
)

included_parts = select(\
    parts.c.sub_part, parts.c.part, parts.c.quantity\
    ).\
    where(parts.c.part=='our part').\
    cte(recursive=True)


incl_alias = included_parts.alias()
parts_alias = parts.alias()
included_parts = included_parts.union_all(
    select(
        parts_alias.c.sub_part,
        parts_alias.c.part,
        parts_alias.c.quantity
    ).\
    where(parts_alias.c.part==incl_alias.c.sub_part)
)

statement = select(
            included_parts.c.sub_part,
            func.sum(included_parts.c.quantity).
              label('total_quantity')
        ).\
        group_by(included_parts.c.sub_part)

result = conn.execute(statement).fetchall()

Example 3, an upsert using UPDATE and INSERT with CTEs:

from datetime import date
from sqlalchemy import (MetaData, Table, Column, Integer,
                        Date, select, literal, and_, exists)

metadata = MetaData()

visitors = Table('visitors', metadata,
    Column('product_id', Integer, primary_key=True),
    Column('date', Date, primary_key=True),
    Column('count', Integer),
)

# add 5 visitors for the product_id == 1
product_id = 1
day = date.today()
count = 5

update_cte = (
    visitors.update()
    .where(and_(visitors.c.product_id == product_id,
                visitors.c.date == day))
    .values(count=visitors.c.count + count)
    .returning(literal(1))
    .cte('update_cte')
)

upsert = visitors.insert().from_select(
    [visitors.c.product_id, visitors.c.date, visitors.c.count],
    select(literal(product_id), literal(day), literal(count))
        .where(~exists(update_cte.select()))
)

connection.execute(upsert)

Example 4, Nesting CTE (SQLAlchemy 1.4.24 and above):

value_a = select(
    literal("root").label("n")
).cte("value_a")

# A nested CTE with the same name as the root one
value_a_nested = select(
    literal("nesting").label("n")
).cte("value_a", nesting=True)

# Nesting CTEs takes ascendency locally
# over the CTEs at a higher level
value_b = select(value_a_nested.c.n).cte("value_b")

value_ab = select(value_a.c.n.label("a"), value_b.c.n.label("b"))

The above query will render the second CTE nested inside the first, shown with inline parameters below as:

WITH
    value_a AS
        (SELECT 'root' AS n),
    value_b AS
        (WITH value_a AS
            (SELECT 'nesting' AS n)
        SELECT value_a.n AS n FROM value_a)
SELECT value_a.n AS a, value_b.n AS b
FROM value_a, value_b

The same CTE can be set up using the HasCTE.add_cte() method as follows (SQLAlchemy 2.0 and above):

value_a = select(
    literal("root").label("n")
).cte("value_a")

# A nested CTE with the same name as the root one
value_a_nested = select(
    literal("nesting").label("n")
).cte("value_a")

# Nesting CTEs takes ascendency locally
# over the CTEs at a higher level
value_b = (
    select(value_a_nested.c.n).
    add_cte(value_a_nested, nest_here=True).
    cte("value_b")
)

value_ab = select(value_a.c.n.label("a"), value_b.c.n.label("b"))

Example 5, Non-Linear CTE (SQLAlchemy 1.4.28 and above):

edge = Table(
    "edge",
    metadata,
    Column("id", Integer, primary_key=True),
    Column("left", Integer),
    Column("right", Integer),
)

root_node = select(literal(1).label("node")).cte(
    "nodes", recursive=True
)

left_edge = select(edge.c.left).join(
    root_node, edge.c.right == root_node.c.node
)
right_edge = select(edge.c.right).join(
    root_node, edge.c.left == root_node.c.node
)

subgraph_cte = root_node.union(left_edge, right_edge)

subgraph = select(subgraph_cte)

The above query will render 2 UNIONs inside the recursive CTE:

WITH RECURSIVE nodes(node) AS (
        SELECT 1 AS node
    UNION
        SELECT edge."left" AS "left"
        FROM edge JOIN nodes ON edge."right" = nodes.node
    UNION
        SELECT edge."right" AS "right"
        FROM edge JOIN nodes ON edge."left" = nodes.node
)
SELECT nodes.node FROM nodes

See also

Query.cte() - ORM version of HasCTE.cte().

method sqlalchemy.sql.expression.SelectBase.exists() → Exists¶

Return an Exists representation of this selectable, which can be used as a column expression.

The returned object is an instance of Exists.

See also

EXISTS subqueries - in the 2.0 style tutorial.

New in version 1.4.

attribute sqlalchemy.sql.expression.SelectBase.exported_columns¶

A ColumnCollection that represents the “exported” columns of this Selectable, not including TextClause constructs.

The “exported” columns for a SelectBase object are synonymous with the SelectBase.selected_columns collection.

New in version 1.4.

See also

Select.selected_columns

method sqlalchemy.sql.expression.SelectBase.get_label_style() → SelectLabelStyle¶

Retrieve the current label style.

Implemented by subclasses.

attribute sqlalchemy.sql.expression.SelectBase.inherit_cache: bool | None = None¶

inherited from the HasCacheKey.inherit_cache attribute of HasCacheKey

Indicate if this HasCacheKey instance should make use of the cache key generation scheme used by its immediate superclass.

The attribute defaults to None, which indicates that a construct has not yet taken into account whether or not its appropriate for it to participate in caching; this is functionally equivalent to setting the value to False, except that a warning is also emitted.

This flag can be set to True on a particular class, if the SQL that corresponds to the object does not change based on attributes which are local to this class, and not its superclass.

See also

Enabling Caching Support for Custom Constructs - General guideslines for setting the HasCacheKey.inherit_cache attribute for third-party or user defined SQL constructs.

method sqlalchemy.sql.expression.SelectBase.is_derived_from(fromclause: FromClause | None) → bool¶

inherited from the ReturnsRows.is_derived_from() method of ReturnsRows

Return True if this ReturnsRows is ‘derived’ from the given FromClause.

An example would be an Alias of a Table is derived from that Table.

method sqlalchemy.sql.expression.SelectBase.label(name: str | None) → Label[Any]¶: Return a ‘scalar’ representation of this selectable, embedded as a subquery with a label.

See also

SelectBase.scalar_subquery().

method sqlalchemy.sql.expression.SelectBase.lateral(name: str | None = None) → LateralFromClause¶

Return a LATERAL alias of this Selectable.

The return value is the Lateral construct also provided by the top-level lateral() function.

See also

LATERAL correlation - overview of usage.

method sqlalchemy.sql.expression.SelectBase.replace_selectable(old: FromClause, alias: Alias) → Self¶: inherited from the Selectable.replace_selectable() method of Selectable

Replace all occurrences of FromClause ‘old’ with the given Alias object, returning a copy of this FromClause.

Deprecated since version 1.4: The Selectable.replace_selectable() method is deprecated, and will be removed in a future release. Similar functionality is available via the sqlalchemy.sql.visitors module.

method sqlalchemy.sql.expression.SelectBase.scalar_subquery() → ScalarSelect[Any]¶

Return a ‘scalar’ representation of this selectable, which can be used as a column expression.

The returned object is an instance of ScalarSelect.

Typically, a select statement which has only one column in its columns clause is eligible to be used as a scalar expression. The scalar subquery can then be used in the WHERE clause or columns clause of an enclosing SELECT.

Note that the scalar subquery differentiates from the FROM-level subquery that can be produced using the SelectBase.subquery() method.

See also

Scalar and Correlated Subqueries - in the 2.0 tutorial

method sqlalchemy.sql.expression.SelectBase.select(*arg: Any, **kw: Any) → Select¶: Deprecated since version 1.4: The SelectBase.select() method is deprecated and will be removed in a future release; this method implicitly creates a subquery that should be explicit. Please call SelectBase.subquery() first in order to create a subquery, which then can be selected.

attribute sqlalchemy.sql.expression.SelectBase.selected_columns¶

A ColumnCollection representing the columns that this SELECT statement or similar construct returns in its result set.

This collection differs from the FromClause.columns collection of a FromClause in that the columns within this collection cannot be directly nested inside another SELECT statement; a subquery must be applied first which provides for the necessary parenthesization required by SQL.

Note

The SelectBase.selected_columns collection does not include expressions established in the columns clause using the text() construct; these are silently omitted from the collection. To use plain textual column expressions inside of a Select construct, use the literal_column() construct.

See also

New in version 1.4.

method sqlalchemy.sql.expression.SelectBase.set_label_style(style: SelectLabelStyle) → Self¶

Return a new selectable with the specified label style.

Implemented by subclasses.

method sqlalchemy.sql.expression.SelectBase.subquery(name: str | None = None) → Subquery¶

Return a subquery of this SelectBase.

A subquery is from a SQL perspective a parenthesized, named construct that can be placed in the FROM clause of another SELECT statement.

Given a SELECT statement such as:

stmt = select(table.c.id, table.c.name)

The above statement might look like:

SELECT table.id, table.name FROM table

The subquery form by itself renders the same way, however when embedded into the FROM clause of another SELECT statement, it becomes a named sub-element:

subq = stmt.subquery()
new_stmt = select(subq)

The above renders as:

SELECT anon_1.id, anon_1.name
FROM (SELECT table.id, table.name FROM table) AS anon_1

Historically, SelectBase.subquery() is equivalent to calling the FromClause.alias() method on a FROM object; however, as a SelectBase object is not directly FROM object, the SelectBase.subquery() method provides clearer semantics.

New in version 1.4.

class sqlalchemy.sql.expression.Subquery¶

Represent a subquery of a SELECT.

A Subquery is created by invoking the SelectBase.subquery() method, or for convenience the SelectBase.alias() method, on any SelectBase subclass which includes Select, CompoundSelect, and TextualSelect. As rendered in a FROM clause, it represents the body of the SELECT statement inside of parenthesis, followed by the usual “AS <somename>” that defines all “alias” objects.

The Subquery object is very similar to the Alias object and can be used in an equivalent way. The difference between Alias and Subquery is that Alias always contains a FromClause object whereas Subquery always contains a SelectBase object.

New in version 1.4: The Subquery class was added which now serves the purpose of providing an aliased version of a SELECT statement.

Members

as_scalar(), inherit_cache

Class signature

class sqlalchemy.sql.expression.Subquery (sqlalchemy.sql.expression.AliasedReturnsRows)

method sqlalchemy.sql.expression.Subquery.as_scalar() → ScalarSelect[Any]¶: Deprecated since version 1.4: The Subquery.as_scalar() method, which was previously Alias.as_scalar() prior to version 1.4, is deprecated and will be removed in a future release; Please use the Select.scalar_subquery() method of the select() construct before constructing a subquery object, or with the ORM use the Query.scalar_subquery() method.

attribute sqlalchemy.sql.expression.Subquery.inherit_cache: bool | None = True¶

Indicate if this HasCacheKey instance should make use of the cache key generation scheme used by its immediate superclass.

The attribute defaults to None, which indicates that a construct has not yet taken into account whether or not its appropriate for it to participate in caching; this is functionally equivalent to setting the value to False, except that a warning is also emitted.

This flag can be set to True on a particular class, if the SQL that corresponds to the object does not change based on attributes which are local to this class, and not its superclass.

See also

Enabling Caching Support for Custom Constructs - General guideslines for setting the HasCacheKey.inherit_cache attribute for third-party or user defined SQL constructs.

class sqlalchemy.sql.expression.TableClause¶

Represents a minimal “table” construct.

This is a lightweight table object that has only a name, a collection of columns, which are typically produced by the column() function, and a schema:

from sqlalchemy import table, column

user = table("user",
        column("id"),
        column("name"),
        column("description"),
)

The TableClause construct serves as the base for the more commonly used Table object, providing the usual set of FromClause services including the .c. collection and statement generation methods.

It does not provide all the additional schema-level services of Table, including constraints, references to other tables, or support for MetaData-level services. It’s useful on its own as an ad-hoc construct used to generate quick SQL statements when a more fully fledged Table is not on hand.

Class signature

class sqlalchemy.sql.expression.TableClause (sqlalchemy.sql.roles.DMLTableRole, sqlalchemy.sql.expression.Immutable, sqlalchemy.sql.expression.NamedFromClause)

method sqlalchemy.sql.expression.TableClause.alias(name: str | None = None, flat: bool = False) → NamedFromClause¶

inherited from the FromClause.alias() method of FromClause

Return an alias of this FromClause.

E.g.:

a2 = some_table.alias('a2')

The above code creates an Alias object which can be used as a FROM clause in any SELECT statement.

See also

attribute sqlalchemy.sql.expression.TableClause.c¶

inherited from the FromClause.c attribute of FromClause

A synonym for FromClause.columns

Returns:: a ColumnCollection

attribute sqlalchemy.sql.expression.TableClause.columns¶

inherited from the FromClause.columns attribute of FromClause

A named-based collection of ColumnElement objects maintained by this FromClause.

The columns, or c collection, is the gateway to the construction of SQL expressions using table-bound or other selectable-bound columns:

select(mytable).where(mytable.c.somecolumn == 5)

Returns:: a ColumnCollection object.

method sqlalchemy.sql.expression.TableClause.compare(other: ClauseElement, **kw: Any) → bool¶

inherited from the ClauseElement.compare() method of ClauseElement

Compare this ClauseElement to the given ClauseElement.

Subclasses should override the default behavior, which is a straight identity comparison.

**kw are arguments consumed by subclass compare() methods and may be used to modify the criteria for comparison (see ColumnElement).

method sqlalchemy.sql.expression.TableClause.compile(bind: Engine | Connection | None = None, dialect: Dialect | None = None, **kw: Any) → Compiled¶

inherited from the CompilerElement.compile() method of CompilerElement

Compile this SQL expression.

The return value is a Compiled object. Calling str() or unicode() on the returned value will yield a string representation of the result. The Compiled object also can return a dictionary of bind parameter names and values using the params accessor.

Parameters:

bind – An Connection or Engine which can provide a Dialect in order to generate a Compiled object. If the bind and dialect parameters are both omitted, a default SQL compiler is used.
column_keys – Used for INSERT and UPDATE statements, a list of column names which should be present in the VALUES clause of the compiled statement. If None, all columns from the target table object are rendered.
dialect – A Dialect instance which can generate a Compiled object. This argument takes precedence over the bind argument.
compile_kwargs –
optional dictionary of additional parameters that will be passed through to the compiler within all “visit” methods. This allows any custom flag to be passed through to a custom compilation construct, for example. It is also used for the case of passing the literal_binds flag through:
```
from sqlalchemy.sql import table, column, select

t = table('t', column('x'))

s = select(t).where(t.c.x == 5)

print(s.compile(compile_kwargs={"literal_binds": True}))
```

method sqlalchemy.sql.expression.TableClause.corresponding_column(column: KeyedColumnElement[Any], require_embedded: bool = False) → KeyedColumnElement[Any] | None¶

inherited from the Selectable.corresponding_column() method of Selectable

Given a ColumnElement, return the exported ColumnElement object from the Selectable.exported_columns collection of this Selectable which corresponds to that original ColumnElement via a common ancestor column.

Parameters:

column – the target ColumnElement to be matched.
require_embedded – only return corresponding columns for the given ColumnElement, if the given ColumnElement is actually present within a sub-element of this Selectable. Normally the column will match if it merely shares a common ancestor with one of the exported columns of this Selectable.

See also

Selectable.exported_columns - the ColumnCollection that is used for the operation.

ColumnCollection.corresponding_column() - implementation method.

method sqlalchemy.sql.expression.TableClause.delete() → Delete¶

Generate a delete() construct against this TableClause.

E.g.:

table.delete().where(table.c.id==7)

See delete() for argument and usage information.

attribute sqlalchemy.sql.expression.TableClause.description¶

attribute sqlalchemy.sql.expression.TableClause.entity_namespace¶

inherited from the FromClause.entity_namespace attribute of FromClause

Return a namespace used for name-based access in SQL expressions.

This is the namespace that is used to resolve “filter_by()” type expressions, such as:

stmt.filter_by(address='some address')

It defaults to the .c collection, however internally it can be overridden using the “entity_namespace” annotation to deliver alternative results.

attribute sqlalchemy.sql.expression.TableClause.exported_columns¶

inherited from the FromClause.exported_columns attribute of FromClause

A ColumnCollection that represents the “exported” columns of this Selectable.

The “exported” columns for a FromClause object are synonymous with the FromClause.columns collection.

New in version 1.4.

See also

Table.foreign_key_constraints

attribute sqlalchemy.sql.expression.TableClause.foreign_keys¶

inherited from the FromClause.foreign_keys attribute of FromClause

Return the collection of ForeignKey marker objects which this FromClause references.

Each ForeignKey is a member of a Table-wide ForeignKeyConstraint.

See also

method sqlalchemy.sql.expression.TableClause.get_children(*, omit_attrs: Tuple[str, ...] = (), **kw: Any) → Iterable[HasTraverseInternals]¶

inherited from the HasTraverseInternals.get_children() method of HasTraverseInternals

Return immediate child HasTraverseInternals elements of this HasTraverseInternals.

This is used for visit traversal.

**kw may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

attribute sqlalchemy.sql.expression.TableClause.implicit_returning = False¶: TableClause doesn’t support having a primary key or column -level defaults, so implicit returning doesn’t apply.

attribute sqlalchemy.sql.expression.TableClause.inherit_cache: bool | None = None¶

inherited from the HasCacheKey.inherit_cache attribute of HasCacheKey

Indicate if this HasCacheKey instance should make use of the cache key generation scheme used by its immediate superclass.

The attribute defaults to None, which indicates that a construct has not yet taken into account whether or not its appropriate for it to participate in caching; this is functionally equivalent to setting the value to False, except that a warning is also emitted.

This flag can be set to True on a particular class, if the SQL that corresponds to the object does not change based on attributes which are local to this class, and not its superclass.

See also

Enabling Caching Support for Custom Constructs - General guideslines for setting the HasCacheKey.inherit_cache attribute for third-party or user defined SQL constructs.

method sqlalchemy.sql.expression.TableClause.insert() → Insert¶

Generate an Insert construct against this TableClause.

E.g.:

table.insert().values(name='foo')

See insert() for argument and usage information.

method sqlalchemy.sql.expression.TableClause.is_derived_from(fromclause: FromClause | None) → bool¶

inherited from the FromClause.is_derived_from() method of FromClause

Return True if this FromClause is ‘derived’ from the given FromClause.

An example would be an Alias of a Table is derived from that Table.

method sqlalchemy.sql.expression.TableClause.join(right: _FromClauseArgument, onclause: _ColumnExpressionArgument[bool] | None = None, isouter: bool = False, full: bool = False) → Join¶

inherited from the FromClause.join() method of FromClause

Return a Join from this FromClause to another FromClause.

E.g.:

from sqlalchemy import join

j = user_table.join(address_table,
                user_table.c.id == address_table.c.user_id)
stmt = select(user_table).select_from(j)

would emit SQL along the lines of:

SELECT user.id, user.name FROM user
JOIN address ON user.id = address.user_id

Parameters:

right – the right side of the join; this is any FromClause object such as a Table object, and may also be a selectable-compatible object such as an ORM-mapped class.
onclause – a SQL expression representing the ON clause of the join. If left at None, FromClause.join() will attempt to join the two tables based on a foreign key relationship.
isouter – if True, render a LEFT OUTER JOIN, instead of JOIN.
full – if True, render a FULL OUTER JOIN, instead of LEFT OUTER JOIN. Implies FromClause.join.isouter.

See also

join() - standalone function

Join - the type of object produced

method sqlalchemy.sql.expression.TableClause.lateral(name: str | None = None) → LateralFromClause¶

inherited from the Selectable.lateral() method of Selectable

Return a LATERAL alias of this Selectable.

The return value is the Lateral construct also provided by the top-level lateral() function.

See also

LATERAL correlation - overview of usage.

method sqlalchemy.sql.expression.TableClause.outerjoin(right: _FromClauseArgument, onclause: _ColumnExpressionArgument[bool] | None = None, full: bool = False) → Join¶

inherited from the FromClause.outerjoin() method of FromClause

Return a Join from this FromClause to another FromClause, with the “isouter” flag set to True.

E.g.:

from sqlalchemy import outerjoin

j = user_table.outerjoin(address_table,
                user_table.c.id == address_table.c.user_id)

The above is equivalent to:

j = user_table.join(
    address_table,
    user_table.c.id == address_table.c.user_id,
    isouter=True)

Parameters:

right – the right side of the join; this is any FromClause object such as a Table object, and may also be a selectable-compatible object such as an ORM-mapped class.
onclause – a SQL expression representing the ON clause of the join. If left at None, FromClause.join() will attempt to join the two tables based on a foreign key relationship.
full – if True, render a FULL OUTER JOIN, instead of LEFT OUTER JOIN.

See also

FromClause.join()

Join

method sqlalchemy.sql.expression.TableClause.params(*optionaldict, **kwargs)¶

inherited from the Immutable.params() method of Immutable

Return a copy with bindparam() elements replaced.

Returns a copy of this ClauseElement with bindparam() elements replaced with values taken from the given dictionary:

>>> clause = column('x') + bindparam('foo')
>>> print(clause.compile().params)
{'foo':None}
>>> print(clause.params({'foo':7}).compile().params)
{'foo':7}

attribute sqlalchemy.sql.expression.TableClause.primary_key¶

inherited from the FromClause.primary_key attribute of FromClause

Return the iterable collection of Column objects which comprise the primary key of this _selectable.FromClause.

For a Table object, this collection is represented by the PrimaryKeyConstraint which itself is an iterable collection of Column objects.

method sqlalchemy.sql.expression.TableClause.replace_selectable(old: FromClause, alias: Alias) → Self¶: inherited from the Selectable.replace_selectable() method of Selectable

Replace all occurrences of FromClause ‘old’ with the given Alias object, returning a copy of this FromClause.

Deprecated since version 1.4: The Selectable.replace_selectable() method is deprecated, and will be removed in a future release. Similar functionality is available via the sqlalchemy.sql.visitors module.

attribute sqlalchemy.sql.expression.TableClause.schema: str | None = None¶

inherited from the FromClause.schema attribute of FromClause

Define the ‘schema’ attribute for this FromClause.

This is typically None for most objects except that of Table, where it is taken as the value of the Table.schema argument.

method sqlalchemy.sql.expression.TableClause.select() → Select¶

inherited from the FromClause.select() method of FromClause

Return a SELECT of this FromClause.

e.g.:

stmt = some_table.select().where(some_table.c.id == 5)

See also

select() - general purpose method which allows for arbitrary column lists.

method sqlalchemy.sql.expression.TableClause.self_group(against: OperatorType | None = None) → ClauseElement¶

inherited from the ClauseElement.self_group() method of ClauseElement

Apply a ‘grouping’ to this ClauseElement.

This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by select() constructs when placed into the FROM clause of another select(). (Note that subqueries should be normally created using the Select.alias() method, as many platforms require nested SELECT statements to be named).

As expressions are composed together, the application of self_group() is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like x OR (y AND z) - AND takes precedence over OR.

The base self_group() method of ClauseElement just returns self.

method sqlalchemy.sql.expression.TableClause.table_valued() → TableValuedColumn[Any]¶

inherited from the NamedFromClause.table_valued() method of NamedFromClause

Return a TableValuedColumn object for this FromClause.

A TableValuedColumn is a ColumnElement that represents a complete row in a table. Support for this construct is backend dependent, and is supported in various forms by backends such as PostgreSQL, Oracle and SQL Server.

E.g.:

>>> fromsqlalchemyimportselect,column,func,table>>> a=table("a",column("id"),column("x"),column("y"))>>> stmt=select(func.row_to_json(a.table_valued()))>>> print(stmt)SELECT row_to_json(a) AS row_to_json_1
FROM a

New in version 1.4.0b2.

method sqlalchemy.sql.expression.TableClause.tablesample(sampling: float | Function[Any], name: str | None = None, seed: roles.ExpressionElementRole[Any] | None = None) → TableSample¶

inherited from the FromClause.tablesample() method of FromClause

Return a TABLESAMPLE alias of this FromClause.

The return value is the TableSample construct also provided by the top-level tablesample() function.

See also

tablesample() - usage guidelines and parameters

method sqlalchemy.sql.expression.TableClause.unique_params(*optionaldict, **kwargs)¶

inherited from the Immutable.unique_params() method of Immutable

Return a copy with bindparam() elements replaced.

Same functionality as ClauseElement.params(), except adds unique=True to affected bind parameters so that multiple statements can be used.

method sqlalchemy.sql.expression.TableClause.update() → Update¶

Generate an update() construct against this TableClause.

E.g.:

table.update().where(table.c.id==7).values(name='foo')

See update() for argument and usage information.

class sqlalchemy.sql.expression.TableSample¶

Represent a TABLESAMPLE clause.

This object is constructed from the tablesample() module level function as well as the FromClause.tablesample() method available on all FromClause subclasses.

See also

tablesample()

Class signature

class sqlalchemy.sql.expression.TableSample (sqlalchemy.sql.expression.FromClauseAlias)

class sqlalchemy.sql.expression.TableValuedAlias¶

An alias against a “table valued” SQL function.

This construct provides for a SQL function that returns columns to be used in the FROM clause of a SELECT statement. The object is generated using the FunctionElement.table_valued() method, e.g.:

>>> fromsqlalchemyimportselect,func>>> fn=func.json_array_elements_text('["one", "two", "three"]').table_valued("value")>>> print(select(fn.c.value))SELECT anon_1.value
FROM json_array_elements_text(:json_array_elements_text_1) AS anon_1

New in version 1.4.0b2.

Members

alias(), column, lateral(), render_derived()

Class signature

class sqlalchemy.sql.expression.TableValuedAlias (sqlalchemy.sql.expression.LateralFromClause, sqlalchemy.sql.expression.Alias)

method sqlalchemy.sql.expression.TableValuedAlias.alias(name: str | None = None, flat: bool = False) → TableValuedAlias¶

Return a new alias of this TableValuedAlias.

This creates a distinct FROM object that will be distinguished from the original one when used in a SQL statement.

attribute sqlalchemy.sql.expression.TableValuedAlias.column¶

Return a column expression representing this TableValuedAlias.

This accessor is used to implement the FunctionElement.column_valued() method. See that method for further details.

E.g.:

>>> print(select(func.some_func().table_valued("value").column))SELECT anon_1 FROM some_func() AS anon_1

See also

FunctionElement.column_valued()

method sqlalchemy.sql.expression.TableValuedAlias.lateral(name: str | None = None) → LateralFromClause¶: Return a new TableValuedAlias with the lateral flag set, so that it renders as LATERAL.

See also

lateral()

method sqlalchemy.sql.expression.TableValuedAlias.render_derived(name: str | None = None, with_types: bool = False) → TableValuedAlias¶

Apply “render derived” to this TableValuedAlias.

This has the effect of the individual column names listed out after the alias name in the “AS” sequence, e.g.:

>>> print(...     select(...         func.unnest(array(["one", "two", "three"])).            table_valued("x", with_ordinality="o").render_derived()...     )... )SELECT anon_1.x, anon_1.o
FROM unnest(ARRAY[%(param_1)s, %(param_2)s, %(param_3)s]) WITH ORDINALITY AS anon_1(x, o)

The with_types keyword will render column types inline within the alias expression (this syntax currently applies to the PostgreSQL database):

>>> print(...     select(...         func.json_to_recordset(...             '[{"a":1,"b":"foo"},{"a":"2","c":"bar"}]'...         )...         .table_valued(column("a", Integer), column("b", String))...         .render_derived(with_types=True)...     )... )SELECT anon_1.a, anon_1.b FROM json_to_recordset(:json_to_recordset_1)
AS anon_1(a INTEGER, b VARCHAR)

Parameters:

name – optional string name that will be applied to the alias generated. If left as None, a unique anonymizing name will be used.
with_types – if True, the derived columns will include the datatype specification with each column. This is a special syntax currently known to be required by PostgreSQL for some SQL functions.

class sqlalchemy.sql.expression.TextualSelect¶

Wrap a TextClause construct within a SelectBase interface.

This allows the TextClause object to gain a .c collection and other FROM-like capabilities such as FromClause.alias(), SelectBase.cte(), etc.

The TextualSelect construct is produced via the TextClause.columns() method - see that method for details.

Changed in version 1.4: the TextualSelect class was renamed from TextAsFrom, to more correctly suit its role as a SELECT-oriented object and not a FROM clause.

See also

text()

TextClause.columns() - primary creation interface.

Class signature

class sqlalchemy.sql.expression.TextualSelect (sqlalchemy.sql.expression.SelectBase, sqlalchemy.sql.expression.ExecutableReturnsRows, sqlalchemy.sql.expression.Generative)

method sqlalchemy.sql.expression.TextualSelect.add_cte(*ctes: CTE, nest_here: bool = False) → Self¶

inherited from the HasCTE.add_cte() method of HasCTE

Add one or more CTE constructs to this statement.

This method will associate the given CTE constructs with the parent statement such that they will each be unconditionally rendered in the WITH clause of the final statement, even if not referenced elsewhere within the statement or any sub-selects.

The optional HasCTE.add_cte.nest_here parameter when set to True will have the effect that each given CTE will render in a WITH clause rendered directly along with this statement, rather than being moved to the top of the ultimate rendered statement, even if this statement is rendered as a subquery within a larger statement.

This method has two general uses. One is to embed CTE statements that serve some purpose without being referenced explicitly, such as the use case of embedding a DML statement such as an INSERT or UPDATE as a CTE inline with a primary statement that may draw from its results indirectly. The other is to provide control over the exact placement of a particular series of CTE constructs that should remain rendered directly in terms of a particular statement that may be nested in a larger statement.

E.g.:

from sqlalchemy import table, column, select
t = table('t', column('c1'), column('c2'))

ins = t.insert().values({"c1": "x", "c2": "y"}).cte()

stmt = select(t).add_cte(ins)

Would render:

WITH anon_1 AS
(INSERT INTO t (c1, c2) VALUES (:param_1, :param_2))
SELECT t.c1, t.c2
FROM t

Above, the “anon_1” CTE is not referenced in the SELECT statement, however still accomplishes the task of running an INSERT statement.

Similarly in a DML-related context, using the PostgreSQL Insert construct to generate an “upsert”:

from sqlalchemy import table, column
from sqlalchemy.dialects.postgresql import insert

t = table("t", column("c1"), column("c2"))

delete_statement_cte = (
    t.delete().where(t.c.c1 < 1).cte("deletions")
)

insert_stmt = insert(t).values({"c1": 1, "c2": 2})
update_statement = insert_stmt.on_conflict_do_update(
    index_elements=[t.c.c1],
    set_={
        "c1": insert_stmt.excluded.c1,
        "c2": insert_stmt.excluded.c2,
    },
).add_cte(delete_statement_cte)

print(update_statement)

The above statement renders as:

WITH deletions AS
(DELETE FROM t WHERE t.c1 < %(c1_1)s)
INSERT INTO t (c1, c2) VALUES (%(c1)s, %(c2)s)
ON CONFLICT (c1) DO UPDATE SET c1 = excluded.c1, c2 = excluded.c2

New in version 1.4.21.

Parameters:

*ctes –
zero or more CTE constructs.

Changed in version 2.0: Multiple CTE instances are accepted
nest_here –
if True, the given CTE or CTEs will be rendered as though they specified the HasCTE.cte.nesting flag to True when they were added to this HasCTE. Assuming the given CTEs are not referenced in an outer-enclosing statement as well, the CTEs given should render at the level of this statement when this flag is given.

New in version 2.0.

See also

HasCTE.cte.nesting

method sqlalchemy.sql.expression.TextualSelect.alias(name: str | None = None, flat: bool = False) → Subquery¶

inherited from the SelectBase.alias() method of SelectBase

Return a named subquery against this SelectBase.

For a SelectBase (as opposed to a FromClause), this returns a Subquery object which behaves mostly the same as the Alias object that is used with a FromClause.

Changed in version 1.4: The SelectBase.alias() method is now a synonym for the SelectBase.subquery() method.

method sqlalchemy.sql.expression.TextualSelect.as_scalar() → ScalarSelect[Any]¶: inherited from the SelectBase.as_scalar() method of SelectBase

Deprecated since version 1.4: The SelectBase.as_scalar() method is deprecated and will be removed in a future release. Please refer to SelectBase.scalar_subquery().

attribute sqlalchemy.sql.expression.TextualSelect.c¶: inherited from the SelectBase.c attribute of SelectBase

Deprecated since version 1.4: The SelectBase.c and SelectBase.columns attributes are deprecated and will be removed in a future release; these attributes implicitly create a subquery that should be explicit. Please call SelectBase.subquery() first in order to create a subquery, which then contains this attribute. To access the columns that this SELECT object SELECTs from, use the SelectBase.selected_columns attribute.

method sqlalchemy.sql.expression.TextualSelect.compare(other: ClauseElement, **kw: Any) → bool¶

inherited from the ClauseElement.compare() method of ClauseElement

Compare this ClauseElement to the given ClauseElement.

Subclasses should override the default behavior, which is a straight identity comparison.

**kw are arguments consumed by subclass compare() methods and may be used to modify the criteria for comparison (see ColumnElement).

method sqlalchemy.sql.expression.TextualSelect.compile(bind: Engine | Connection | None = None, dialect: Dialect | None = None, **kw: Any) → Compiled¶

inherited from the CompilerElement.compile() method of CompilerElement

Compile this SQL expression.

The return value is a Compiled object. Calling str() or unicode() on the returned value will yield a string representation of the result. The Compiled object also can return a dictionary of bind parameter names and values using the params accessor.

Parameters:

bind – An Connection or Engine which can provide a Dialect in order to generate a Compiled object. If the bind and dialect parameters are both omitted, a default SQL compiler is used.
column_keys – Used for INSERT and UPDATE statements, a list of column names which should be present in the VALUES clause of the compiled statement. If None, all columns from the target table object are rendered.
dialect – A Dialect instance which can generate a Compiled object. This argument takes precedence over the bind argument.
compile_kwargs –
optional dictionary of additional parameters that will be passed through to the compiler within all “visit” methods. This allows any custom flag to be passed through to a custom compilation construct, for example. It is also used for the case of passing the literal_binds flag through:
```
from sqlalchemy.sql import table, column, select

t = table('t', column('x'))

s = select(t).where(t.c.x == 5)

print(s.compile(compile_kwargs={"literal_binds": True}))
```

method sqlalchemy.sql.expression.TextualSelect.corresponding_column(column: KeyedColumnElement[Any], require_embedded: bool = False) → KeyedColumnElement[Any] | None¶

inherited from the Selectable.corresponding_column() method of Selectable

Given a ColumnElement, return the exported ColumnElement object from the Selectable.exported_columns collection of this Selectable which corresponds to that original ColumnElement via a common ancestor column.

Parameters:

column – the target ColumnElement to be matched.
require_embedded – only return corresponding columns for the given ColumnElement, if the given ColumnElement is actually present within a sub-element of this Selectable. Normally the column will match if it merely shares a common ancestor with one of the exported columns of this Selectable.

See also

Selectable.exported_columns - the ColumnCollection that is used for the operation.

ColumnCollection.corresponding_column() - implementation method.

method sqlalchemy.sql.expression.TextualSelect.cte(name: str | None = None, recursive: bool = False, nesting: bool = False) → CTE¶

inherited from the HasCTE.cte() method of HasCTE

Return a new CTE, or Common Table Expression instance.

Common table expressions are a SQL standard whereby SELECT statements can draw upon secondary statements specified along with the primary statement, using a clause called “WITH”. Special semantics regarding UNION can also be employed to allow “recursive” queries, where a SELECT statement can draw upon the set of rows that have previously been selected.

CTEs can also be applied to DML constructs UPDATE, INSERT and DELETE on some databases, both as a source of CTE rows when combined with RETURNING, as well as a consumer of CTE rows.

SQLAlchemy detects CTE objects, which are treated similarly to Alias objects, as special elements to be delivered to the FROM clause of the statement as well as to a WITH clause at the top of the statement.

For special prefixes such as PostgreSQL “MATERIALIZED” and “NOT MATERIALIZED”, the CTE.prefix_with() method may be used to establish these.

Changed in version 1.3.13: Added support for prefixes. In particular - MATERIALIZED and NOT MATERIALIZED.

Parameters:

name – name given to the common table expression. Like FromClause.alias(), the name can be left as None in which case an anonymous symbol will be used at query compile time.
recursive – if True, will render WITH RECURSIVE. A recursive common table expression is intended to be used in conjunction with UNION ALL in order to derive rows from those already selected.
nesting –
if True, will render the CTE locally to the statement in which it is referenced. For more complex scenarios, the HasCTE.add_cte() method using the HasCTE.add_cte.nest_here parameter may also be used to more carefully control the exact placement of a particular CTE.

New in version 1.4.24.

See also

HasCTE.add_cte()

The following examples include two from PostgreSQL’s documentation at https://www.postgresql.org/docs/current/static/queries-with.html, as well as additional examples.

Example 1, non recursive:

from sqlalchemy import (Table, Column, String, Integer,
                        MetaData, select, func)

metadata = MetaData()

orders = Table('orders', metadata,
    Column('region', String),
    Column('amount', Integer),
    Column('product', String),
    Column('quantity', Integer)
)

regional_sales = select(
                    orders.c.region,
                    func.sum(orders.c.amount).label('total_sales')
                ).group_by(orders.c.region).cte("regional_sales")


top_regions = select(regional_sales.c.region).\
        where(
            regional_sales.c.total_sales >
            select(
                func.sum(regional_sales.c.total_sales) / 10
            )
        ).cte("top_regions")

statement = select(
            orders.c.region,
            orders.c.product,
            func.sum(orders.c.quantity).label("product_units"),
            func.sum(orders.c.amount).label("product_sales")
    ).where(orders.c.region.in_(
        select(top_regions.c.region)
    )).group_by(orders.c.region, orders.c.product)

result = conn.execute(statement).fetchall()

Example 2, WITH RECURSIVE:

from sqlalchemy import (Table, Column, String, Integer,
                        MetaData, select, func)

metadata = MetaData()

parts = Table('parts', metadata,
    Column('part', String),
    Column('sub_part', String),
    Column('quantity', Integer),
)

included_parts = select(\
    parts.c.sub_part, parts.c.part, parts.c.quantity\
    ).\
    where(parts.c.part=='our part').\
    cte(recursive=True)


incl_alias = included_parts.alias()
parts_alias = parts.alias()
included_parts = included_parts.union_all(
    select(
        parts_alias.c.sub_part,
        parts_alias.c.part,
        parts_alias.c.quantity
    ).\
    where(parts_alias.c.part==incl_alias.c.sub_part)
)

statement = select(
            included_parts.c.sub_part,
            func.sum(included_parts.c.quantity).
              label('total_quantity')
        ).\
        group_by(included_parts.c.sub_part)

result = conn.execute(statement).fetchall()

Example 3, an upsert using UPDATE and INSERT with CTEs:

from datetime import date
from sqlalchemy import (MetaData, Table, Column, Integer,
                        Date, select, literal, and_, exists)

metadata = MetaData()

visitors = Table('visitors', metadata,
    Column('product_id', Integer, primary_key=True),
    Column('date', Date, primary_key=True),
    Column('count', Integer),
)

# add 5 visitors for the product_id == 1
product_id = 1
day = date.today()
count = 5

update_cte = (
    visitors.update()
    .where(and_(visitors.c.product_id == product_id,
                visitors.c.date == day))
    .values(count=visitors.c.count + count)
    .returning(literal(1))
    .cte('update_cte')
)

upsert = visitors.insert().from_select(
    [visitors.c.product_id, visitors.c.date, visitors.c.count],
    select(literal(product_id), literal(day), literal(count))
        .where(~exists(update_cte.select()))
)

connection.execute(upsert)

Example 4, Nesting CTE (SQLAlchemy 1.4.24 and above):

value_a = select(
    literal("root").label("n")
).cte("value_a")

# A nested CTE with the same name as the root one
value_a_nested = select(
    literal("nesting").label("n")
).cte("value_a", nesting=True)

# Nesting CTEs takes ascendency locally
# over the CTEs at a higher level
value_b = select(value_a_nested.c.n).cte("value_b")

value_ab = select(value_a.c.n.label("a"), value_b.c.n.label("b"))

The above query will render the second CTE nested inside the first, shown with inline parameters below as:

WITH
    value_a AS
        (SELECT 'root' AS n),
    value_b AS
        (WITH value_a AS
            (SELECT 'nesting' AS n)
        SELECT value_a.n AS n FROM value_a)
SELECT value_a.n AS a, value_b.n AS b
FROM value_a, value_b

The same CTE can be set up using the HasCTE.add_cte() method as follows (SQLAlchemy 2.0 and above):

value_a = select(
    literal("root").label("n")
).cte("value_a")

# A nested CTE with the same name as the root one
value_a_nested = select(
    literal("nesting").label("n")
).cte("value_a")

# Nesting CTEs takes ascendency locally
# over the CTEs at a higher level
value_b = (
    select(value_a_nested.c.n).
    add_cte(value_a_nested, nest_here=True).
    cte("value_b")
)

value_ab = select(value_a.c.n.label("a"), value_b.c.n.label("b"))

Example 5, Non-Linear CTE (SQLAlchemy 1.4.28 and above):

edge = Table(
    "edge",
    metadata,
    Column("id", Integer, primary_key=True),
    Column("left", Integer),
    Column("right", Integer),
)

root_node = select(literal(1).label("node")).cte(
    "nodes", recursive=True
)

left_edge = select(edge.c.left).join(
    root_node, edge.c.right == root_node.c.node
)
right_edge = select(edge.c.right).join(
    root_node, edge.c.left == root_node.c.node
)

subgraph_cte = root_node.union(left_edge, right_edge)

subgraph = select(subgraph_cte)

The above query will render 2 UNIONs inside the recursive CTE:

WITH RECURSIVE nodes(node) AS (
        SELECT 1 AS node
    UNION
        SELECT edge."left" AS "left"
        FROM edge JOIN nodes ON edge."right" = nodes.node
    UNION
        SELECT edge."right" AS "right"
        FROM edge JOIN nodes ON edge."left" = nodes.node
)
SELECT nodes.node FROM nodes

See also

Query.cte() - ORM version of HasCTE.cte().

method sqlalchemy.sql.expression.TextualSelect.execution_options(**kw: Any) → Self¶

inherited from the Executable.execution_options() method of Executable

Set non-SQL options for the statement which take effect during execution.

Execution options can be set at many scopes, including per-statement, per-connection, or per execution, using methods such as Connection.execution_options() and parameters which accept a dictionary of options such as Connection.execute.execution_options and Session.execute.execution_options.

The primary characteristic of an execution option, as opposed to other kinds of options such as ORM loader options, is that execution options never affect the compiled SQL of a query, only things that affect how the SQL statement itself is invoked or how results are fetched. That is, execution options are not part of what’s accommodated by SQL compilation nor are they considered part of the cached state of a statement.

The Executable.execution_options() method is generative, as is the case for the method as applied to the Engine and Query objects, which means when the method is called, a copy of the object is returned, which applies the given parameters to that new copy, but leaves the original unchanged:

statement = select(table.c.x, table.c.y)
new_statement = statement.execution_options(my_option=True)

An exception to this behavior is the Connection object, where the Connection.execution_options() method is explicitly not generative.

The kinds of options that may be passed to Executable.execution_options() and other related methods and parameter dictionaries include parameters that are explicitly consumed by SQLAlchemy Core or ORM, as well as arbitrary keyword arguments not defined by SQLAlchemy, which means the methods and/or parameter dictionaries may be used for user-defined parameters that interact with custom code, which may access the parameters using methods such as Executable.get_execution_options() and Connection.get_execution_options(), or within selected event hooks using a dedicated execution_options event parameter such as ConnectionEvents.before_execute.execution_options or ORMExecuteState.execution_options, e.g.:

from sqlalchemy import event

@event.listens_for(some_engine, "before_execute")
def _process_opt(conn, statement, multiparams, params, execution_options):
    "run a SQL function before invoking a statement"

    if execution_options.get("do_special_thing", False):
        conn.exec_driver_sql("run_special_function()")

Within the scope of options that are explicitly recognized by SQLAlchemy, most apply to specific classes of objects and not others. The most common execution options include:

Connection.execution_options.isolation_level - sets the isolation level for a connection or a class of connections via an Engine. This option is accepted only by Connection or Engine.
Connection.execution_options.stream_results - indicates results should be fetched using a server side cursor; this option is accepted by Connection, by the Connection.execute.execution_options parameter on Connection.execute(), and additionally by Executable.execution_options() on a SQL statement object, as well as by ORM constructs like Session.execute().
Connection.execution_options.compiled_cache - indicates a dictionary that will serve as the SQL compilation cache for a Connection or Engine, as well as for ORM methods like Session.execute(). Can be passed as None to disable caching for statements. This option is not accepted by Executable.execution_options() as it is inadvisable to carry along a compilation cache within a statement object.
Connection.execution_options.schema_translate_map - a mapping of schema names used by the Schema Translate Map feature, accepted by Connection, Engine, Executable, as well as by ORM constructs like Session.execute().

See also

ORM Execution Options - documentation on all ORM-specific execution options

method sqlalchemy.sql.expression.TextualSelect.exists() → Exists¶

inherited from the SelectBase.exists() method of SelectBase

Return an Exists representation of this selectable, which can be used as a column expression.

The returned object is an instance of Exists.

See also

EXISTS subqueries - in the 2.0 style tutorial.

New in version 1.4.

attribute sqlalchemy.sql.expression.TextualSelect.exported_columns¶

inherited from the SelectBase.exported_columns attribute of SelectBase

A ColumnCollection that represents the “exported” columns of this Selectable, not including TextClause constructs.

The “exported” columns for a SelectBase object are synonymous with the SelectBase.selected_columns collection.

New in version 1.4.

See also

method sqlalchemy.sql.expression.TextualSelect.get_children(*, omit_attrs: Tuple[str, ...] = (), **kw: Any) → Iterable[HasTraverseInternals]¶

inherited from the HasTraverseInternals.get_children() method of HasTraverseInternals

Return immediate child HasTraverseInternals elements of this HasTraverseInternals.

This is used for visit traversal.

**kw may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).

method sqlalchemy.sql.expression.TextualSelect.get_execution_options() → _ExecuteOptions¶: inherited from the Executable.get_execution_options() method of Executable

Get the non-SQL options which will take effect during execution.

New in version 1.3.

See also

Executable.execution_options()

method sqlalchemy.sql.expression.TextualSelect.get_label_style() → SelectLabelStyle¶

inherited from the SelectBase.get_label_style() method of SelectBase

Retrieve the current label style.

Implemented by subclasses.

attribute sqlalchemy.sql.expression.TextualSelect.inherit_cache: bool | None = None¶

inherited from the HasCacheKey.inherit_cache attribute of HasCacheKey

Indicate if this HasCacheKey instance should make use of the cache key generation scheme used by its immediate superclass.

The attribute defaults to None, which indicates that a construct has not yet taken into account whether or not its appropriate for it to participate in caching; this is functionally equivalent to setting the value to False, except that a warning is also emitted.

This flag can be set to True on a particular class, if the SQL that corresponds to the object does not change based on attributes which are local to this class, and not its superclass.

See also

Enabling Caching Support for Custom Constructs - General guideslines for setting the HasCacheKey.inherit_cache attribute for third-party or user defined SQL constructs.

method sqlalchemy.sql.expression.TextualSelect.is_derived_from(fromclause: FromClause | None) → bool¶

inherited from the ReturnsRows.is_derived_from() method of ReturnsRows

Return True if this ReturnsRows is ‘derived’ from the given FromClause.

An example would be an Alias of a Table is derived from that Table.

method sqlalchemy.sql.expression.TextualSelect.label(name: str | None) → Label[Any]¶: inherited from the SelectBase.label() method of SelectBase

Return a ‘scalar’ representation of this selectable, embedded as a subquery with a label.

See also

SelectBase.scalar_subquery().

method sqlalchemy.sql.expression.TextualSelect.lateral(name: str | None = None) → LateralFromClause¶

inherited from the SelectBase.lateral() method of SelectBase

Return a LATERAL alias of this Selectable.

The return value is the Lateral construct also provided by the top-level lateral() function.

See also

LATERAL correlation - overview of usage.

method sqlalchemy.sql.expression.TextualSelect.options(*options: ExecutableOption) → Self¶

inherited from the Executable.options() method of Executable

Apply options to this statement.

In the general sense, options are any kind of Python object that can be interpreted by the SQL compiler for the statement. These options can be consumed by specific dialects or specific kinds of compilers.

The most commonly known kind of option are the ORM level options that apply “eager load” and other loading behaviors to an ORM query. However, options can theoretically be used for many other purposes.

For background on specific kinds of options for specific kinds of statements, refer to the documentation for those option objects.

Changed in version 1.4: - added Executable.options() to Core statement objects towards the goal of allowing unified Core / ORM querying capabilities.

See also

Column Loading Options - refers to options specific to the usage of ORM queries

Relationship Loading with Loader Options - refers to options specific to the usage of ORM queries

method sqlalchemy.sql.expression.TextualSelect.params(_ClauseElement__optionaldict: Mapping[str, Any] | None = None, **kwargs: Any) → Self¶

inherited from the ClauseElement.params() method of ClauseElement

Return a copy with bindparam() elements replaced.

Returns a copy of this ClauseElement with bindparam() elements replaced with values taken from the given dictionary:

>>> clause = column('x') + bindparam('foo')
>>> print(clause.compile().params)
{'foo':None}
>>> print(clause.params({'foo':7}).compile().params)
{'foo':7}

method sqlalchemy.sql.expression.TextualSelect.replace_selectable(old: FromClause, alias: Alias) → Self¶: inherited from the Selectable.replace_selectable() method of Selectable

Replace all occurrences of FromClause ‘old’ with the given Alias object, returning a copy of this FromClause.

Deprecated since version 1.4: The Selectable.replace_selectable() method is deprecated, and will be removed in a future release. Similar functionality is available via the sqlalchemy.sql.visitors module.

method sqlalchemy.sql.expression.TextualSelect.scalar_subquery() → ScalarSelect[Any]¶

inherited from the SelectBase.scalar_subquery() method of SelectBase

Return a ‘scalar’ representation of this selectable, which can be used as a column expression.

The returned object is an instance of ScalarSelect.

Typically, a select statement which has only one column in its columns clause is eligible to be used as a scalar expression. The scalar subquery can then be used in the WHERE clause or columns clause of an enclosing SELECT.

Note that the scalar subquery differentiates from the FROM-level subquery that can be produced using the SelectBase.subquery() method.

See also

Scalar and Correlated Subqueries - in the 2.0 tutorial

method sqlalchemy.sql.expression.TextualSelect.select(*arg: Any, **kw: Any) → Select¶: inherited from the SelectBase.select() method of SelectBase

Deprecated since version 1.4: The SelectBase.select() method is deprecated and will be removed in a future release; this method implicitly creates a subquery that should be explicit. Please call SelectBase.subquery() first in order to create a subquery, which then can be selected.

attribute sqlalchemy.sql.expression.TextualSelect.selected_columns¶

A ColumnCollection representing the columns that this SELECT statement or similar construct returns in its result set, not including TextClause constructs.

This collection differs from the FromClause.columns collection of a FromClause in that the columns within this collection cannot be directly nested inside another SELECT statement; a subquery must be applied first which provides for the necessary parenthesization required by SQL.

For a TextualSelect construct, the collection contains the ColumnElement objects that were passed to the constructor, typically via the TextClause.columns() method.

New in version 1.4.

method sqlalchemy.sql.expression.TextualSelect.self_group(against: OperatorType | None = None) → ClauseElement¶

inherited from the ClauseElement.self_group() method of ClauseElement

Apply a ‘grouping’ to this ClauseElement.

This method is overridden by subclasses to return a “grouping” construct, i.e. parenthesis. In particular it’s used by “binary” expressions to provide a grouping around themselves when placed into a larger expression, as well as by select() constructs when placed into the FROM clause of another select(). (Note that subqueries should be normally created using the Select.alias() method, as many platforms require nested SELECT statements to be named).

As expressions are composed together, the application of self_group() is automatic - end-user code should never need to use this method directly. Note that SQLAlchemy’s clause constructs take operator precedence into account - so parenthesis might not be needed, for example, in an expression like x OR (y AND z) - AND takes precedence over OR.

The base self_group() method of ClauseElement just returns self.

method sqlalchemy.sql.expression.TextualSelect.set_label_style(style: SelectLabelStyle) → TextualSelect¶

Return a new selectable with the specified label style.

Implemented by subclasses.

method sqlalchemy.sql.expression.TextualSelect.subquery(name: str | None = None) → Subquery¶

inherited from the SelectBase.subquery() method of SelectBase

Return a subquery of this SelectBase.

A subquery is from a SQL perspective a parenthesized, named construct that can be placed in the FROM clause of another SELECT statement.

Given a SELECT statement such as:

stmt = select(table.c.id, table.c.name)

The above statement might look like:

SELECT table.id, table.name FROM table

The subquery form by itself renders the same way, however when embedded into the FROM clause of another SELECT statement, it becomes a named sub-element:

subq = stmt.subquery()
new_stmt = select(subq)

The above renders as:

SELECT anon_1.id, anon_1.name
FROM (SELECT table.id, table.name FROM table) AS anon_1

Historically, SelectBase.subquery() is equivalent to calling the FromClause.alias() method on a FROM object; however, as a SelectBase object is not directly FROM object, the SelectBase.subquery() method provides clearer semantics.

New in version 1.4.

method sqlalchemy.sql.expression.TextualSelect.unique_params(_ClauseElement__optionaldict: Dict[str, Any] | None = None, **kwargs: Any) → Self¶

inherited from the ClauseElement.unique_params() method of ClauseElement

Return a copy with bindparam() elements replaced.

Same functionality as ClauseElement.params(), except adds unique=True to affected bind parameters so that multiple statements can be used.

class sqlalchemy.sql.expression.Values¶

Represent a VALUES construct that can be used as a FROM element in a statement.

The Values object is created from the values() function.

New in version 1.4.

Members

alias(), data(), lateral(), scalar_values()

Class signature

class sqlalchemy.sql.expression.Values (sqlalchemy.sql.roles.InElementRole, sqlalchemy.sql.expression.Generative, sqlalchemy.sql.expression.LateralFromClause)

method sqlalchemy.sql.expression.Values.alias(name: str | None = None, flat: bool = False) → Self¶

Return a new Values construct that is a copy of this one with the given name.

This method is a VALUES-specific specialization of the FromClause.alias() method.

See also