Column Elements and Expressions

The expression API consists of a series of classes that each represent a specific lexical element within a SQL string. Composed together into a larger structure, they form a statement construct that may be compiled into a string representation that can be passed to a database. The classes are organized into a hierarchy that begins at the basemost ClauseElement class. Key subclasses include ColumnElement, which represents the role of any column-based expression in a SQL statement, such as in the columns clause, WHERE clause, and ORDER BY clause, and FromClause, which represents the role of a token that is placed in the FROM clause of a SELECT statement.

Object Name	Description
all_(expr)	Produce an ALL expression.
and_(*clauses)	Produce a conjunction of expressions joined by AND.
any_(expr)	Produce an ANY expression.
asc(column)	Produce an ascending ORDER BY clause element.
between(expr, lower_bound, upper_bound[, symmetric])	Produce a BETWEEN predicate clause.
BinaryExpression	Represent an expression that is LEFT <operator> RIGHT.
bindparam(key[, value, type_, unique, ...])	Produce a “bound expression”.
BindParameter	Represent a “bound expression”.
case(whens[, value, else_])	Produce a CASE expression.
Case	Represent a CASE expression.
cast(expression, type_)	Produce a CAST expression.
Cast	Represent a CAST expression.
ClauseElement	Base class for elements of a programmatically constructed SQL expression.
ClauseList	Describe a list of clauses, separated by an operator.
collate(expression, collation)	Return the clause expression COLLATE collation.
column(text[, type_, is_literal, _selectable])	Produce a ColumnClause object.
ColumnClause	Represents a column expression from any textual string.
ColumnCollection	An ordered dictionary that stores a list of ColumnElement instances.
ColumnElement	Represent a column-oriented SQL expression suitable for usage in the “columns” clause, WHERE clause etc. of a statement.
ColumnOperators	Defines boolean, comparison, and other operators for ColumnElement expressions.
custom_op	Represent a ‘custom’ operator.
desc(column)	Produce a descending ORDER BY clause element.
DialectKWArgs	Establish the ability for a class to have dialect-specific arguments with defaults and constructor validation.
distinct(expr)	Produce an column-expression-level unary DISTINCT clause.
extract(field, expr, **kwargs)	Return a Extract construct.
Extract	Represent a SQL EXTRACT clause, extract(field FROM expr).
false()	Return a False_ construct.
False_	Represent the false keyword, or equivalent, in a SQL statement.
func	Generate Function objects based on getattr calls.
funcfilter(func, *criterion)	Produce a FunctionFilter object against a function.
FunctionFilter	Represent a function FILTER clause.
label(name, element[, type_])	Return a Label object for the given ColumnElement.
Label	Represents a column label (AS).
literal(value[, type_])	Return a literal clause, bound to a bind parameter.
literal_column(text[, type_])	Produce a ColumnClause object that has the column.is_literal flag set to True.
not_(clause)	Return a negation of the given clause, i.e. NOT(clause).
null()	Return a constant Null construct.
Null	Represent the NULL keyword in a SQL statement.
nullsfirst(column)	Produce the NULLS FIRST modifier for an ORDER BY expression.
nullslast(column)	Produce the NULLS LAST modifier for an ORDER BY expression.
Operators	Base of comparison and logical operators.
or_(*clauses)	Produce a conjunction of expressions joined by OR.
outparam(key[, type_])	Create an ‘OUT’ parameter for usage in functions (stored procedures), for databases which support them.
over(element[, partition_by, order_by, range_, ...])	Produce an Over object against a function.
Over	Represent an OVER clause.
quoted_name	Represent a SQL identifier combined with quoting preferences.
text(text[, bind, bindparams, typemap, ...])	Construct a new TextClause clause, representing a textual SQL string directly.
TextClause	Represent a literal SQL text fragment.
true()	Return a constant True_ construct.
True_	Represent the true keyword, or equivalent, in a SQL statement.
Tuple	Represent a SQL tuple.
tuple_(*clauses, **kw)	Return a Tuple.
type_coerce(expression, type_)	Associate a SQL expression with a particular type, without rendering CAST.
TypeCoerce	Represent a Python-side type-coercion wrapper.
UnaryExpression	Define a ‘unary’ expression.
within_group(element, *order_by)	Produce a WithinGroup object against a function.
WithinGroup	Represent a WITHIN GROUP (ORDER BY) clause.

function sqlalchemy.sql.expression.all_(expr)

Produce an ALL expression.

This may apply to an array type for some dialects (e.g. postgresql), or to a subquery for others (e.g. mysql). e.g.:

# postgresql '5 = ALL (somearray)'
expr = 5 == all_(mytable.c.somearray)

# mysql '5 = ALL (SELECT value FROM table)'
expr = 5 == all_(select([table.c.value]))

New in version 1.1.

See also

any_()

function sqlalchemy.sql.expression.and_(*clauses)

Produce a conjunction of expressions joined by AND.

E.g.:

from sqlalchemy import and_

stmt = select([users_table]).where(
                and_(
                    users_table.c.name == 'wendy',
                    users_table.c.enrolled == True
                )
            )

The and_() conjunction is also available using the Python & operator (though note that compound expressions need to be parenthesized in order to function with Python operator precedence behavior):

stmt = select([users_table]).where(
                (users_table.c.name == 'wendy') &
                (users_table.c.enrolled == True)
            )

The and_() operation is also implicit in some cases; the Select.where() method for example can be invoked multiple times against a statement, which will have the effect of each clause being combined using and_():

stmt = select([users_table]).                        where(users_table.c.name == 'wendy').                        where(users_table.c.enrolled == True)

See also

or_()

function sqlalchemy.sql.expression.any_(expr)

Produce an ANY expression.

This may apply to an array type for some dialects (e.g. postgresql), or to a subquery for others (e.g. mysql). e.g.:

# postgresql '5 = ANY (somearray)'
expr = 5 == any_(mytable.c.somearray)

# mysql '5 = ANY (SELECT value FROM table)'
expr = 5 == any_(select([table.c.value]))

New in version 1.1.

See also

all_()

function sqlalchemy.sql.expression.asc(column)

Produce an ascending ORDER BY clause element.

e.g.:

from sqlalchemy import asc
stmt = select([users_table]).order_by(asc(users_table.c.name))

will produce SQL as:

SELECT id, name FROM user ORDER BY name ASC

The asc() function is a standalone version of the ColumnElement.asc() method available on all SQL expressions, e.g.:

stmt = select([users_table]).order_by(users_table.c.name.asc())

Parameters:

column – A ColumnElement (e.g. scalar SQL expression) with which to apply the asc() operation.

See also

desc()

nullsfirst()

nullslast()

Select.order_by()

function sqlalchemy.sql.expression.between(expr, lower_bound, upper_bound, symmetric=False)

Produce a BETWEEN predicate clause.

E.g.:

from sqlalchemy import between
stmt = select([users_table]).where(between(users_table.c.id, 5, 7))

Would produce SQL resembling:

SELECT id, name FROM user WHERE id BETWEEN :id_1 AND :id_2

The between() function is a standalone version of the ColumnElement.between() method available on all SQL expressions, as in:

stmt = select([users_table]).where(users_table.c.id.between(5, 7))

All arguments passed to between(), including the left side column expression, are coerced from Python scalar values if a the value is not a ColumnElement subclass. For example, three fixed values can be compared as in:

print(between(5, 3, 7))

Which would produce:

:param_1 BETWEEN :param_2 AND :param_3

Parameters:

• expr – a column expression, typically a ColumnElement instance or alternatively a Python scalar expression to be coerced into a column expression, serving as the left side of the BETWEEN expression.

• lower_bound – a column or Python scalar expression serving as the lower bound of the right side of the BETWEEN expression.

• upper_bound – a column or Python scalar expression serving as the upper bound of the right side of the BETWEEN expression.

• symmetric –

  if True, will render “ BETWEEN SYMMETRIC “. Note that not all databases support this syntax.

  New in version 0.9.5.

See also

ColumnElement.between()

function sqlalchemy.sql.expression.bindparam(key, value=symbol('NO_ARG'), type_=None, unique=False, required=symbol('NO_ARG'), quote=None, callable_=None, expanding=False, isoutparam=False, _compared_to_operator=None, _compared_to_type=None)

Produce a “bound expression”.

The return value is an instance of BindParameter; this is a ColumnElement subclass which represents a so-called “placeholder” value in a SQL expression, the value of which is supplied at the point at which the statement in executed against a database connection.

In SQLAlchemy, the bindparam() construct has the ability to carry along the actual value that will be ultimately used at expression time. In this way, it serves not just as a “placeholder” for eventual population, but also as a means of representing so-called “unsafe” values which should not be rendered directly in a SQL statement, but rather should be passed along to the DBAPI as values which need to be correctly escaped and potentially handled for type-safety.

When using bindparam() explicitly, the use case is typically one of traditional deferment of parameters; the bindparam() construct accepts a name which can then be referred to at execution time:

from sqlalchemy import bindparam

stmt = select([users_table]).\
            where(users_table.c.name == bindparam('username'))

The above statement, when rendered, will produce SQL similar to:

SELECT id, name FROM user WHERE name = :username

In order to populate the value of :username above, the value would typically be applied at execution time to a method like Connection.execute():

result = connection.execute(stmt, username='wendy')

Explicit use of bindparam() is also common when producing UPDATE or DELETE statements that are to be invoked multiple times, where the WHERE criterion of the statement is to change on each invocation, such as:

stmt = (users_table.update().
        where(user_table.c.name == bindparam('username')).
        values(fullname=bindparam('fullname'))
        )

connection.execute(
    stmt, [{"username": "wendy", "fullname": "Wendy Smith"},
           {"username": "jack", "fullname": "Jack Jones"},
           ]
)

SQLAlchemy’s Core expression system makes wide use of bindparam() in an implicit sense. It is typical that Python literal values passed to virtually all SQL expression functions are coerced into fixed bindparam() constructs. For example, given a comparison operation such as:

expr = users_table.c.name == 'Wendy'

The above expression will produce a BinaryExpression construct, where the left side is the Column object representing the name column, and the right side is a BindParameter representing the literal value:

print(repr(expr.right))
BindParameter('%(4327771088 name)s', 'Wendy', type_=String())

The expression above will render SQL such as:

user.name = :name_1

Where the :name_1 parameter name is an anonymous name. The actual string Wendy is not in the rendered string, but is carried along where it is later used within statement execution. If we invoke a statement like the following:

stmt = select([users_table]).where(users_table.c.name == 'Wendy')
result = connection.execute(stmt)

We would see SQL logging output as:

SELECT "user".id, "user".name
FROM "user"
WHERE "user".name = %(name_1)s
{'name_1': 'Wendy'}

Above, we see that Wendy is passed as a parameter to the database, while the placeholder :name_1 is rendered in the appropriate form for the target database, in this case the PostgreSQL database.

Similarly, bindparam() is invoked automatically when working with CRUD statements as far as the “VALUES” portion is concerned. The insert() construct produces an INSERT expression which will, at statement execution time, generate bound placeholders based on the arguments passed, as in:

stmt = users_table.insert()
result = connection.execute(stmt, name='Wendy')

The above will produce SQL output as:

INSERT INTO "user" (name) VALUES (%(name)s)
{'name': 'Wendy'}

The Insert construct, at compilation/execution time, rendered a single bindparam() mirroring the column name name as a result of the single name parameter we passed to the Connection.execute() method.

Parameters:

• key – the key (e.g. the name) for this bind param. Will be used in the generated SQL statement for dialects that use named parameters. This value may be modified when part of a compilation operation, if other BindParameter objects exist with the same key, or if its length is too long and truncation is required.

• value – Initial value for this bind param. Will be used at statement execution time as the value for this parameter passed to the DBAPI, if no other value is indicated to the statement execution method for this particular parameter name. Defaults to None.

• callable_ – A callable function that takes the place of “value”. The function will be called at statement execution time to determine the ultimate value. Used for scenarios where the actual bind value cannot be determined at the point at which the clause construct is created, but embedded bind values are still desirable.

• type_ –

  A TypeEngine class or instance representing an optional datatype for this bindparam(). If not passed, a type may be determined automatically for the bind, based on the given value; for example, trivial Python types such as str, int, bool may result in the String, Integer or Boolean types being automatically selected.

  The type of a bindparam() is significant especially in that the type will apply pre-processing to the value before it is passed to the database. For example, a bindparam() which refers to a datetime value, and is specified as holding the DateTime type, may apply conversion needed to the value (such as stringification on SQLite) before passing the value to the database.

• unique – if True, the key name of this BindParameter will be modified if another BindParameter of the same name already has been located within the containing expression. This flag is used generally by the internals when producing so-called “anonymous” bound expressions, it isn’t generally applicable to explicitly-named bindparam() constructs.

• required – If True, a value is required at execution time. If not passed, it defaults to True if neither bindparam.value or bindparam.callable were passed. If either of these parameters are present, then bindparam.required defaults to False.

• quote – True if this parameter name requires quoting and is not currently known as a SQLAlchemy reserved word; this currently only applies to the Oracle backend, where bound names must sometimes be quoted.

• isoutparam – if True, the parameter should be treated like a stored procedure “OUT” parameter. This applies to backends such as Oracle which support OUT parameters.

• expanding –

  if True, this parameter will be treated as an “expanding” parameter at execution time; the parameter value is expected to be a sequence, rather than a scalar value, and the string SQL statement will be transformed on a per-execution basis to accommodate the sequence with a variable number of parameter slots passed to the DBAPI. This is to allow statement caching to be used in conjunction with an IN clause.

  See also

  ColumnOperators.in_()

  Using IN expressions - with baked queries

  Note

  The “expanding” feature does not support “executemany”- style parameter sets. In the 1.2 series it does not support empty IN expressions, however it does support these in version 1.3.

  New in version 1.2.

See also

Bind Parameter Objects

Insert Expressions

outparam()

function sqlalchemy.sql.expression.case(whens, value=None, else_=None)

Produce a CASE expression.

The CASE construct in SQL is a conditional object that acts somewhat analogously to an “if/then” construct in other languages. It returns an instance of Case.

case() in its usual form is passed a list of “when” constructs, that is, a list of conditions and results as tuples:

from sqlalchemy import case

stmt = select([users_table]).\
            where(
                case(
                    [
                        (users_table.c.name == 'wendy', 'W'),
                        (users_table.c.name == 'jack', 'J')
                    ],
                    else_='E'
                )
            )

The above statement will produce SQL resembling:

SELECT id, name FROM user
WHERE CASE
    WHEN (name = :name_1) THEN :param_1
    WHEN (name = :name_2) THEN :param_2
    ELSE :param_3
END

When simple equality expressions of several values against a single parent column are needed, case() also has a “shorthand” format used via the case.value parameter, which is passed a column expression to be compared. In this form, the case.whens parameter is passed as a dictionary containing expressions to be compared against keyed to result expressions. The statement below is equivalent to the preceding statement:

stmt = select([users_table]).\
            where(
                case(
                    {"wendy": "W", "jack": "J"},
                    value=users_table.c.name,
                    else_='E'
                )
            )

The values which are accepted as result values in case.whens as well as with case.else_ are coerced from Python literals into bindparam() constructs. SQL expressions, e.g. ColumnElement constructs, are accepted as well. To coerce a literal string expression into a constant expression rendered inline, use the literal_column() construct, as in:

from sqlalchemy import case, literal_column

case(
    [
        (
            orderline.c.qty > 100,
            literal_column("'greaterthan100'")
        ),
        (
            orderline.c.qty > 10,
            literal_column("'greaterthan10'")
        )
    ],
    else_=literal_column("'lessthan10'")
)

The above will render the given constants without using bound parameters for the result values (but still for the comparison values), as in:

CASE
    WHEN (orderline.qty > :qty_1) THEN 'greaterthan100'
    WHEN (orderline.qty > :qty_2) THEN 'greaterthan10'
    ELSE 'lessthan10'
END

Parameters:

• whens –

  The criteria to be compared against, case.whens accepts two different forms, based on whether or not case.value is used.

  In the first form, it accepts a list of 2-tuples; each 2-tuple consists of (<sql expression>, <value>), where the SQL expression is a boolean expression and “value” is a resulting value, e.g.:

  case([
      (users_table.c.name == 'wendy', 'W'),
      (users_table.c.name == 'jack', 'J')
  ])

  In the second form, it accepts a Python dictionary of comparison values mapped to a resulting value; this form requires case.value to be present, and values will be compared using the == operator, e.g.:

  case(
      {"wendy": "W", "jack": "J"},
      value=users_table.c.name
  )

• value – An optional SQL expression which will be used as a fixed “comparison point” for candidate values within a dictionary passed to case.whens.

• else_ – An optional SQL expression which will be the evaluated result of the CASE construct if all expressions within case.whens evaluate to false. When omitted, most databases will produce a result of NULL if none of the “when” expressions evaluate to true.

function sqlalchemy.sql.expression.cast(expression, type_)

Produce a CAST expression.

cast() returns an instance of Cast.

E.g.:

from sqlalchemy import cast, Numeric

stmt = select([
            cast(product_table.c.unit_price, Numeric(10, 4))
        ])

The above statement will produce SQL resembling:

SELECT CAST(unit_price AS NUMERIC(10, 4)) FROM product

The cast() function performs two distinct functions when used. The first is that it renders the CAST expression within the resulting SQL string. The second is that it associates the given type (e.g. TypeEngine class or instance) with the column expression on the Python side, which means the expression will take on the expression operator behavior associated with that type, as well as the bound-value handling and result-row-handling behavior of the type.

Changed in version 0.9.0: cast() now applies the given type to the expression such that it takes effect on the bound-value, e.g. the Python-to-database direction, in addition to the result handling, e.g. database-to-Python, direction.

An alternative to cast() is the type_coerce() function. This function performs the second task of associating an expression with a specific type, but does not render the CAST expression in SQL.

Parameters:

• expression – A SQL expression, such as a ColumnElement expression or a Python string which will be coerced into a bound literal value.

• type_ – A TypeEngine class or instance indicating the type to which the CAST should apply.

See also

type_coerce() - Python-side type coercion without emitting CAST.

function sqlalchemy.sql.expression.column(text, type_=None, is_literal=False, _selectable=None)

Produce a ColumnClause object.

The ColumnClause is a lightweight analogue to the Column class. The column() function can be invoked with just a name alone, as in:

from sqlalchemy import column

id, name = column("id"), column("name")
stmt = select([id, name]).select_from("user")

The above statement would produce SQL like:

SELECT id, name FROM user

Once constructed, column() may be used like any other SQL expression element such as within select() constructs:

from sqlalchemy.sql import column

id, name = column("id"), column("name")
stmt = select([id, name]).select_from("user")

The text handled by column() is assumed to be handled like the name of a database column; if the string contains mixed case, special characters, or matches a known reserved word on the target backend, the column expression will render using the quoting behavior determined by the backend. To produce a textual SQL expression that is rendered exactly without any quoting, use literal_column() instead, or pass True as the value of column.is_literal. Additionally, full SQL statements are best handled using the text() construct.

column() can be used in a table-like fashion by combining it with the table() function (which is the lightweight analogue to Table) to produce a working table construct with minimal boilerplate:

from sqlalchemy import table, column, select

user = table("user",
        column("id"),
        column("name"),
        column("description"),
)

stmt = select([user.c.description]).where(user.c.name == 'wendy')

A column() / table() construct like that illustrated above can be created in an ad-hoc fashion and is not associated with any MetaData, DDL, or events, unlike its Table counterpart.

Changed in version 1.0.0: column() can now be imported from the plain sqlalchemy namespace like any other SQL element.

Parameters:

• text – the text of the element.

• type – TypeEngine object which can associate this ColumnClause with a type.

• is_literal – if True, the ColumnClause is assumed to be an exact expression that will be delivered to the output with no quoting rules applied regardless of case sensitive settings. the literal_column() function essentially invokes column() while passing is_literal=True.

See also

Column

literal_column()

table()

text()

Using More Specific Text with table(), literal_column(), and column()

function sqlalchemy.sql.expression.collate(expression, collation)

Return the clause expression COLLATE collation.

e.g.:

collate(mycolumn, 'utf8_bin')

produces:

mycolumn COLLATE utf8_bin

The collation expression is also quoted if it is a case sensitive identifier, e.g. contains uppercase characters.

Changed in version 1.2: quoting is automatically applied to COLLATE expressions if they are case sensitive.

function sqlalchemy.sql.expression.desc(column)

Produce a descending ORDER BY clause element.

e.g.:

from sqlalchemy import desc

stmt = select([users_table]).order_by(desc(users_table.c.name))

will produce SQL as:

SELECT id, name FROM user ORDER BY name DESC

The desc() function is a standalone version of the ColumnElement.desc() method available on all SQL expressions, e.g.:

stmt = select([users_table]).order_by(users_table.c.name.desc())

Parameters:

column – A ColumnElement (e.g. scalar SQL expression) with which to apply the desc() operation.

See also

asc()

nullsfirst()

nullslast()

Select.order_by()

function sqlalchemy.sql.expression.distinct(expr)

Produce an column-expression-level unary DISTINCT clause.

This applies the DISTINCT keyword to an individual column expression, and is typically contained within an aggregate function, as in:

from sqlalchemy import distinct, func
stmt = select([func.count(distinct(users_table.c.name))])

The above would produce an expression resembling:

SELECT COUNT(DISTINCT name) FROM user

The distinct() function is also available as a column-level method, e.g. ColumnElement.distinct(), as in:

stmt = select([func.count(users_table.c.name.distinct())])

The distinct() operator is different from the Select.distinct() method of Select, which produces a SELECT statement with DISTINCT applied to the result set as a whole, e.g. a SELECT DISTINCT expression. See that method for further information.

See also

ColumnElement.distinct()

Select.distinct()

func

function sqlalchemy.sql.expression.extract(field, expr, **kwargs)

Return a Extract construct.

This is typically available as extract() as well as func.extract from the func namespace.

function sqlalchemy.sql.expression.false()

Return a False_ construct.

E.g.:

>>> from sqlalchemy import false
>>> print select([t.c.x]).where(false())
SELECT x FROM t WHERE false

A backend which does not support true/false constants will render as an expression against 1 or 0:

>>> print select([t.c.x]).where(false())
SELECT x FROM t WHERE 0 = 1

The true() and false() constants also feature “short circuit” operation within an and_() or or_() conjunction:

>>> print select([t.c.x]).where(or_(t.c.x > 5, true()))
SELECT x FROM t WHERE true

>>> print select([t.c.x]).where(and_(t.c.x > 5, false()))
SELECT x FROM t WHERE false

Changed in version 0.9: true() and false() feature better integrated behavior within conjunctions and on dialects that don’t support true/false constants.

See also

true()

sqlalchemy.sql.expression.func = <sqlalchemy.sql.functions._FunctionGenerator object>

Generate Function objects based on getattr calls.

function sqlalchemy.sql.expression.funcfilter(func, *criterion)

Produce a FunctionFilter object against a function.

Used against aggregate and window functions, for database backends that support the “FILTER” clause.

E.g.:

from sqlalchemy import funcfilter
funcfilter(func.count(1), MyClass.name == 'some name')

Would produce “COUNT(1) FILTER (WHERE myclass.name = ‘some name’)”.

This function is also available from the func construct itself via the FunctionElement.filter() method.

New in version 1.0.0.

See also

FunctionElement.filter()

function sqlalchemy.sql.expression.label(name, element, type_=None)

Return a Label object for the given ColumnElement.

A label changes the name of an element in the columns clause of a SELECT statement, typically via the AS SQL keyword.

This functionality is more conveniently available via the ColumnElement.label() method on ColumnElement.

Parameters:

• name – label name

• obj – a ColumnElement.

function sqlalchemy.sql.expression.literal(value, type_=None)

Return a literal clause, bound to a bind parameter.

Literal clauses are created automatically when non- ClauseElement objects (such as strings, ints, dates, etc.) are used in a comparison operation with a ColumnElement subclass, such as a Column object. Use this function to force the generation of a literal clause, which will be created as a BindParameter with a bound value.

Parameters:

• value – the value to be bound. Can be any Python object supported by the underlying DB-API, or is translatable via the given type argument.

• type_ – an optional TypeEngine which will provide bind-parameter translation for this literal.

function sqlalchemy.sql.expression.literal_column(text, type_=None)

Produce a ColumnClause object that has the column.is_literal flag set to True.

literal_column() is similar to column(), except that it is more often used as a “standalone” column expression that renders exactly as stated; while column() stores a string name that will be assumed to be part of a table and may be quoted as such, literal_column() can be that, or any other arbitrary column-oriented expression.

Parameters:

• text – the text of the expression; can be any SQL expression. Quoting rules will not be applied. To specify a column-name expression which should be subject to quoting rules, use the column() function.

• type_ – an optional TypeEngine object which will provide result-set translation and additional expression semantics for this column. If left as None the type will be NullType.

See also

column()

text()

Using More Specific Text with table(), literal_column(), and column()

function sqlalchemy.sql.expression.not_(clause)

Return a negation of the given clause, i.e. NOT(clause).

The ~ operator is also overloaded on all ColumnElement subclasses to produce the same result.

function sqlalchemy.sql.expression.null()

Return a constant Null construct.

function sqlalchemy.sql.expression.nullsfirst(column)

Produce the NULLS FIRST modifier for an ORDER BY expression.

nullsfirst() is intended to modify the expression produced by asc() or desc(), and indicates how NULL values should be handled when they are encountered during ordering:

from sqlalchemy import desc, nullsfirst

stmt = select([users_table]).                        order_by(nullsfirst(desc(users_table.c.name)))

The SQL expression from the above would resemble:

SELECT id, name FROM user ORDER BY name DESC NULLS FIRST

Like asc() and desc(), nullsfirst() is typically invoked from the column expression itself using ColumnElement.nullsfirst(), rather than as its standalone function version, as in:

stmt = (select([users_table]).
        order_by(users_table.c.name.desc().nullsfirst())
        )

See also

asc()

desc()

nullslast()

Select.order_by()

function sqlalchemy.sql.expression.nullslast(column)

Produce the NULLS LAST modifier for an ORDER BY expression.

nullslast() is intended to modify the expression produced by asc() or desc(), and indicates how NULL values should be handled when they are encountered during ordering:

from sqlalchemy import desc, nullslast

stmt = select([users_table]).                        order_by(nullslast(desc(users_table.c.name)))

The SQL expression from the above would resemble:

SELECT id, name FROM user ORDER BY name DESC NULLS LAST

Like asc() and desc(), nullslast() is typically invoked from the column expression itself using ColumnElement.nullslast(), rather than as its standalone function version, as in:

stmt = select([users_table]).                        order_by(users_table.c.name.desc().nullslast())

See also

asc()

desc()

nullsfirst()

Select.order_by()

function sqlalchemy.sql.expression.or_(*clauses)

Produce a conjunction of expressions joined by OR.

E.g.:

from sqlalchemy import or_

stmt = select([users_table]).where(
                or_(
                    users_table.c.name == 'wendy',
                    users_table.c.name == 'jack'
                )
            )

The or_() conjunction is also available using the Python | operator (though note that compound expressions need to be parenthesized in order to function with Python operator precedence behavior):

stmt = select([users_table]).where(
                (users_table.c.name == 'wendy') |
                (users_table.c.name == 'jack')
            )

See also

and_()

function sqlalchemy.sql.expression.outparam(key, type_=None)

Create an ‘OUT’ parameter for usage in functions (stored procedures), for databases which support them.

The outparam can be used like a regular function parameter. The “output” value will be available from the ResultProxy object via its out_parameters attribute, which returns a dictionary containing the values.

function sqlalchemy.sql.expression.over(element, partition_by=None, order_by=None, range_=None, rows=None)

Produce an Over object against a function.

Used against aggregate or so-called “window” functions, for database backends that support window functions.

over() is usually called using the FunctionElement.over() method, e.g.:

func.row_number().over(order_by=mytable.c.some_column)

Would produce:

ROW_NUMBER() OVER(ORDER BY some_column)

Ranges are also possible using the over.range_ and over.rows parameters. These mutually-exclusive parameters each accept a 2-tuple, which contains a combination of integers and None:

func.row_number().over(
    order_by=my_table.c.some_column, range_=(None, 0))

The above would produce:

ROW_NUMBER() OVER(ORDER BY some_column
RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)

A value of None indicates “unbounded”, a value of zero indicates “current row”, and negative / positive integers indicate “preceding” and “following”:

• RANGE BETWEEN 5 PRECEDING AND 10 FOLLOWING:

  func.row_number().over(order_by='x', range_=(-5, 10))

• ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW:

  func.row_number().over(order_by='x', rows=(None, 0))

• RANGE BETWEEN 2 PRECEDING AND UNBOUNDED FOLLOWING:

  func.row_number().over(order_by='x', range_=(-2, None))

• RANGE BETWEEN 1 FOLLOWING AND 3 FOLLOWING:

  func.row_number().over(order_by='x', range_=(1, 3))

New in version 1.1: support for RANGE / ROWS within a window

Parameters:

• element – a FunctionElement, WithinGroup, or other compatible construct.

• partition_by – a column element or string, or a list of such, that will be used as the PARTITION BY clause of the OVER construct.

• order_by – a column element or string, or a list of such, that will be used as the ORDER BY clause of the OVER construct.

• range_ –

  optional range clause for the window. This is a tuple value which can contain integer values or None, and will render a RANGE BETWEEN PRECEDING / FOLLOWING clause

  New in version 1.1.

• rows –

  optional rows clause for the window. This is a tuple value which can contain integer values or None, and will render a ROWS BETWEEN PRECEDING / FOLLOWING clause.

  New in version 1.1.

This function is also available from the func construct itself via the FunctionElement.over() method.

See also

func

within_group()

function sqlalchemy.sql.expression.text(text, bind=None, bindparams=None, typemap=None, autocommit=None)

Construct a new TextClause clause, representing a textual SQL string directly.

E.g.:

from sqlalchemy import text

t = text("SELECT * FROM users")
result = connection.execute(t)

The advantages text() provides over a plain string are backend-neutral support for bind parameters, per-statement execution options, as well as bind parameter and result-column typing behavior, allowing SQLAlchemy type constructs to play a role when executing a statement that is specified literally. The construct can also be provided with a .c collection of column elements, allowing it to be embedded in other SQL expression constructs as a subquery.

Bind parameters are specified by name, using the format :name. E.g.:

t = text("SELECT * FROM users WHERE id=:user_id")
result = connection.execute(t, user_id=12)

For SQL statements where a colon is required verbatim, as within an inline string, use a backslash to escape:

t = text("SELECT * FROM users WHERE name='\:username'")

The TextClause construct includes methods which can provide information about the bound parameters as well as the column values which would be returned from the textual statement, assuming it’s an executable SELECT type of statement. The TextClause.bindparams() method is used to provide bound parameter detail, and TextClause.columns() method allows specification of return columns including names and types:

t = text("SELECT * FROM users WHERE id=:user_id").\
        bindparams(user_id=7).\
        columns(id=Integer, name=String)

for id, name in connection.execute(t):
    print(id, name)

The text() construct is used in cases when a literal string SQL fragment is specified as part of a larger query, such as for the WHERE clause of a SELECT statement:

s = select([users.c.id, users.c.name]).where(text("id=:user_id"))
result = connection.execute(s, user_id=12)

text() is also used for the construction of a full, standalone statement using plain text. As such, SQLAlchemy refers to it as an Executable object, and it supports the Executable.execution_options() method. For example, a text() construct that should be subject to “autocommit” can be set explicitly so using the Connection.execution_options.autocommit option:

t = text("EXEC my_procedural_thing()").\
        execution_options(autocommit=True)

Note that SQLAlchemy’s usual “autocommit” behavior applies to text() constructs implicitly - that is, statements which begin with a phrase such as INSERT, UPDATE, DELETE, or a variety of other phrases specific to certain backends, will be eligible for autocommit if no transaction is in progress.

Parameters:

• text – the text of the SQL statement to be created. use :<param> to specify bind parameters; they will be compiled to their engine-specific format.

• autocommit –

  Deprecated since version 0.6: The text.autocommit flag is deprecated and will be removed in a future release. Please use the Connection.execution_options.autocommit parameter in conjunction with the Executable.execution_options() method.

• bind – an optional connection or engine to be used for this text query.

• bindparams –

  A list of bindparam() instances used to provide information about parameters embedded in the statement. E.g.:

  stmt = text("SELECT * FROM table WHERE id=:id",
            bindparams=[bindparam('id', value=5, type_=Integer)])

  Deprecated since version 0.9: the TextClause.bindparams parameter is deprecated and will be removed in a future release. Please refer to the TextClause.bindparams() method.

• typemap –

  A dictionary mapping the names of columns represented in the columns clause of a SELECT statement to type objects, e.g.:

  stmt = text("SELECT * FROM table",
                typemap={'id': Integer, 'name': String},
            )

  Deprecated since version 0.9: The TextClause.typemap argument is deprecated and will be removed in a future release. Please refer to the TextClause.columns() method.

See also

Using Textual SQL - in the Core tutorial

Using Textual SQL - in the ORM tutorial

function sqlalchemy.sql.expression.true()

Return a constant True_ construct.

E.g.:

>>> from sqlalchemy import true
>>> print select([t.c.x]).where(true())
SELECT x FROM t WHERE true

A backend which does not support true/false constants will render as an expression against 1 or 0:

>>> print select([t.c.x]).where(true())
SELECT x FROM t WHERE 1 = 1

The true() and false() constants also feature “short circuit” operation within an and_() or or_() conjunction:

>>> print select([t.c.x]).where(or_(t.c.x > 5, true()))
SELECT x FROM t WHERE true

>>> print select([t.c.x]).where(and_(t.c.x > 5, false()))
SELECT x FROM t WHERE false

Changed in version 0.9: true() and false() feature better integrated behavior within conjunctions and on dialects that don’t support true/false constants.

See also

false()

function sqlalchemy.sql.expression.tuple_(*clauses, **kw)

Return a Tuple.

Main usage is to produce a composite IN construct:

from sqlalchemy import tuple_

tuple_(table.c.col1, table.c.col2).in_(
    [(1, 2), (5, 12), (10, 19)]
)

Warning

The composite IN construct is not supported by all backends, and is currently known to work on PostgreSQL and MySQL, but not SQLite. Unsupported backends will raise a subclass of DBAPIError when such an expression is invoked.

function sqlalchemy.sql.expression.type_coerce(expression, type_)

Associate a SQL expression with a particular type, without rendering CAST.

E.g.:

from sqlalchemy import type_coerce

stmt = select([
    type_coerce(log_table.date_string, StringDateTime())
])

The above construct will produce a TypeCoerce object, which renders SQL that labels the expression, but otherwise does not modify its value on the SQL side:

SELECT date_string AS anon_1 FROM log

When result rows are fetched, the StringDateTime type will be applied to result rows on behalf of the date_string column. The rationale for the “anon_1” label is so that the type-coerced column remains separate in the list of result columns vs. other type-coerced or direct values of the target column. In order to provide a named label for the expression, use ColumnElement.label():

stmt = select([
    type_coerce(
        log_table.date_string, StringDateTime()).label('date')
])

A type that features bound-value handling will also have that behavior take effect when literal values or bindparam() constructs are passed to type_coerce() as targets. For example, if a type implements the TypeEngine.bind_expression() method or TypeEngine.bind_processor() method or equivalent, these functions will take effect at statement compilation/execution time when a literal value is passed, as in:

# bound-value handling of MyStringType will be applied to the
# literal value "some string"
stmt = select([type_coerce("some string", MyStringType)])

type_coerce() is similar to the cast() function, except that it does not render the CAST expression in the resulting statement.

Parameters:

• expression – A SQL expression, such as a ColumnElement expression or a Python string which will be coerced into a bound literal value.

• type_ – A TypeEngine class or instance indicating the type to which the expression is coerced.

See also

cast()

function sqlalchemy.sql.expression.within_group(element, *order_by)

Produce a WithinGroup object against a function.

Used against so-called “ordered set aggregate” and “hypothetical set aggregate” functions, including percentile_cont, rank, dense_rank, etc.

within_group() is usually called using the FunctionElement.within_group() method, e.g.:

from sqlalchemy import within_group
stmt = select([
    department.c.id,
    func.percentile_cont(0.5).within_group(
        department.c.salary.desc()
    )
])

The above statement would produce SQL similar to SELECT department.id, percentile_cont(0.5) WITHIN GROUP (ORDER BY department.salary DESC).

Parameters:

• element – a FunctionElement construct, typically generated by func.

• *order_by – one or more column elements that will be used as the ORDER BY clause of the WITHIN GROUP construct.

New in version 1.1.

See also

func

over()

class sqlalchemy.sql.expression.BinaryExpression(left, right, operator, type_=None, negate=None, modifiers=None)

Represent an expression that is LEFT <operator> RIGHT.

A BinaryExpression is generated automatically whenever two column expressions are used in a Python binary expression:

>>> from sqlalchemy.sql import column
>>> column('a') + column('b')
<sqlalchemy.sql.expression.BinaryExpression object at 0x101029dd0>
>>> print column('a') + column('b')
a + b

Members

compare(), get_children(), self_group()

Class signature

class sqlalchemy.sql.expression.BinaryExpression (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.BinaryExpression.compare(other, **kw)

Compare this BinaryExpression against the given BinaryExpression.

method sqlalchemy.sql.expression.BinaryExpression.get_children(**kwargs)

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs 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.BinaryExpression.self_group(against=None)

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.BindParameter(key, value=symbol('NO_ARG'), type_=None, unique=False, required=symbol('NO_ARG'), quote=None, callable_=None, expanding=False, isoutparam=False, _compared_to_operator=None, _compared_to_type=None)

Represent a “bound expression”.

BindParameter is invoked explicitly using the bindparam() function, as in:

from sqlalchemy import bindparam

stmt = select([users_table]).\
            where(users_table.c.name == bindparam('username'))

Detailed discussion of how BindParameter is used is at bindparam().

See also

bindparam()

Members

__init__(), compare(), effective_value

Class signature

class sqlalchemy.sql.expression.BindParameter (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.BindParameter.__init__(key, value=symbol('NO_ARG'), type_=None, unique=False, required=symbol('NO_ARG'), quote=None, callable_=None, expanding=False, isoutparam=False, _compared_to_operator=None, _compared_to_type=None)

Construct a new BindParameter object.

This constructor is mirrored as a public API function; see bindparam() for a full usage and argument description.

method sqlalchemy.sql.expression.BindParameter.compare(other, **kw)

Compare this BindParameter to the given clause.

attribute sqlalchemy.sql.expression.BindParameter.effective_value

Return the value of this bound parameter, taking into account if the callable parameter was set.

The callable value will be evaluated and returned if present, else value.

class sqlalchemy.sql.expression.Case(whens, value=None, else_=None)

Represent a CASE expression.

Case is produced using the case() factory function, as in:

from sqlalchemy import case

stmt = select([users_table]).                    where(
                case(
                    [
                        (users_table.c.name == 'wendy', 'W'),
                        (users_table.c.name == 'jack', 'J')
                    ],
                    else_='E'
                )
            )

Details on Case usage is at case().

See also

case()

Members

__init__(), get_children()

Class signature

class sqlalchemy.sql.expression.Case (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.Case.__init__(whens, value=None, else_=None)

Construct a new Case object.

This constructor is mirrored as a public API function; see case() for a full usage and argument description.

method sqlalchemy.sql.expression.Case.get_children(**kwargs)

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs 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).

class sqlalchemy.sql.expression.Cast(expression, type_)

Represent a CAST expression.

Cast is produced using the cast() factory function, as in:

from sqlalchemy import cast, Numeric

stmt = select([
            cast(product_table.c.unit_price, Numeric(10, 4))
        ])

Details on Cast usage is at cast().

See also

cast()

Members

__init__(), get_children()

Class signature

class sqlalchemy.sql.expression.Cast (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.Cast.__init__(expression, type_)

Construct a new Cast object.

This constructor is mirrored as a public API function; see cast() for a full usage and argument description.

method sqlalchemy.sql.expression.Cast.get_children(**kwargs)

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs 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).

class sqlalchemy.sql.expression.ClauseElement

Base class for elements of a programmatically constructed SQL expression.

Members

compare(), compile(), get_children(), params(), self_group(), unique_params()

Class signature

class sqlalchemy.sql.expression.ClauseElement (sqlalchemy.sql.visitors.Visitable)

method sqlalchemy.sql.expression.ClauseElement.compare(other, **kw)

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.ClauseElement.compile(default, bind=None, dialect=None, **kw)

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 Engine or Connection from which a Compiled will be acquired. This argument takes precedence over this ClauseElement’s bound engine, if any.

• 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 from which a Compiled will be acquired. This argument takes precedence over the bind argument as well as this ClauseElement’s bound engine, if any.

• inline – Used for INSERT statements, for a dialect which does not support inline retrieval of newly generated primary key columns, will force the expression used to create the new primary key value to be rendered inline within the INSERT statement’s VALUES clause. This typically refers to Sequence execution but may also refer to any server-side default generation function associated with a primary key Column.

• 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})

  New in version 0.9.0.

See also

How do I render SQL expressions as strings, possibly with bound parameters inlined?

method sqlalchemy.sql.expression.ClauseElement.get_children(**kwargs)

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs 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.ClauseElement.params(*optionaldict, **kwargs)

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.ClauseElement.self_group(against=None)

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.ClauseElement.unique_params(*optionaldict, **kwargs)

Return a copy with bindparam() elements replaced.

Same functionality as params(), except adds unique=True to affected bind parameters so that multiple statements can be used.

class sqlalchemy.sql.expression.ClauseList(*clauses, **kwargs)

Describe a list of clauses, separated by an operator.

By default, is comma-separated, such as a column listing.

Members

compare(), get_children(), self_group()

Class signature

class sqlalchemy.sql.expression.ClauseList (sqlalchemy.sql.expression.ClauseElement)

method sqlalchemy.sql.expression.ClauseList.compare(other, **kw)

Compare this ClauseList to the given ClauseList, including a comparison of all the clause items.

method sqlalchemy.sql.expression.ClauseList.get_children(**kwargs)

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs 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.ClauseList.self_group(against=None)

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.ColumnClause(text, type_=None, is_literal=False, _selectable=None)

Represents a column expression from any textual string.

The ColumnClause, a lightweight analogue to the Column class, is typically invoked using the column() function, as in:

from sqlalchemy import column

id, name = column("id"), column("name")
stmt = select([id, name]).select_from("user")

The above statement would produce SQL like:

SELECT id, name FROM user

ColumnClause is the immediate superclass of the schema-specific Column object. While the Column class has all the same capabilities as ColumnClause, the ColumnClause class is usable by itself in those cases where behavioral requirements are limited to simple SQL expression generation. The object has none of the associations with schema-level metadata or with execution-time behavior that Column does, so in that sense is a “lightweight” version of Column.

Full details on ColumnClause usage is at column().

See also

column()

Column

Members

__init__()

Class signature

class sqlalchemy.sql.expression.ColumnClause (sqlalchemy.sql.expression.Immutable, sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.ColumnClause.__init__(text, type_=None, is_literal=False, _selectable=None)

Construct a new ColumnClause object.

This constructor is mirrored as a public API function; see column() for a full usage and argument description.

class sqlalchemy.sql.expression.ColumnCollection(*columns)

An ordered dictionary that stores a list of ColumnElement instances.

Overrides the __eq__() method to produce SQL clauses between sets of correlated columns.

Members

add(), as_immutable(), replace()

Class signature

class sqlalchemy.sql.expression.ColumnCollection (sqlalchemy.util._collections.OrderedProperties)

method sqlalchemy.sql.expression.ColumnCollection.add(column)

Add a column to this collection.

The key attribute of the column will be used as the hash key for this dictionary.

method sqlalchemy.sql.expression.ColumnCollection.as_immutable()

Return an immutable proxy for this Properties.

method sqlalchemy.sql.expression.ColumnCollection.replace(column)

add the given column to this collection, removing unaliased versions of this column as well as existing columns with the same key.

e.g.:

t = Table('sometable', metadata, Column('col1', Integer))
t.columns.replace(Column('col1', Integer, key='columnone'))

will remove the original ‘col1’ from the collection, and add the new column under the name ‘columnname’.

Used by schema.Column to override columns during table reflection.

class sqlalchemy.sql.expression.ColumnElement

Represent a column-oriented SQL expression suitable for usage in the “columns” clause, WHERE clause etc. of a statement.

While the most familiar kind of ColumnElement is the Column object, ColumnElement serves as the basis for any unit that may be present in a SQL expression, including the expressions themselves, SQL functions, bound parameters, literal expressions, keywords such as NULL, etc. ColumnElement is the ultimate base class for all such elements.

A wide variety of SQLAlchemy Core functions work at the SQL expression level, and are intended to accept instances of ColumnElement as arguments. These functions will typically document that they accept a “SQL expression” as an argument. What this means in terms of SQLAlchemy usually refers to an input which is either already in the form of a ColumnElement object, or a value which can be coerced into one. The coercion rules followed by most, but not all, SQLAlchemy Core functions with regards to SQL expressions are as follows:

• a literal Python value, such as a string, integer or floating point value, boolean, datetime, Decimal object, or virtually any other Python object, will be coerced into a “literal bound value”. This generally means that a bindparam() will be produced featuring the given value embedded into the construct; the resulting BindParameter object is an instance of ColumnElement. The Python value will ultimately be sent to the DBAPI at execution time as a parameterized argument to the execute() or executemany() methods, after SQLAlchemy type-specific converters (e.g. those provided by any associated TypeEngine objects) are applied to the value.

• any special object value, typically ORM-level constructs, which feature a method called __clause_element__(). The Core expression system looks for this method when an object of otherwise unknown type is passed to a function that is looking to coerce the argument into a ColumnElement expression. The __clause_element__() method, if present, should return a ColumnElement instance. The primary use of __clause_element__() within SQLAlchemy is that of class-bound attributes on ORM-mapped classes; a User class which contains a mapped attribute named .name will have a method User.name.__clause_element__() which when invoked returns the Column called name associated with the mapped table.

• The Python None value is typically interpreted as NULL, which in SQLAlchemy Core produces an instance of null().

A ColumnElement provides the ability to generate new ColumnElement objects using Python expressions. This means that Python operators such as ==, != and < are overloaded to mimic SQL operations, and allow the instantiation of further ColumnElement instances which are composed from other, more fundamental ColumnElement objects. For example, two ColumnClause objects can be added together with the addition operator + to produce a BinaryExpression. Both ColumnClause and BinaryExpression are subclasses of ColumnElement:

>>> from sqlalchemy.sql import column
>>> column('a') + column('b')
<sqlalchemy.sql.expression.BinaryExpression object at 0x101029dd0>
>>> print column('a') + column('b')
a + b

See also

Column

column()

Members

__eq__(), __le__(), __lt__(), __ne__(), all_(), anon_label, any_(), asc(), base_columns, between(), bind, bool_op(), cast(), collate(), comparator, compare(), compile(), concat(), contains(), desc(), description, distinct(), endswith(), expression, foreign_keys, get_children(), ilike(), in_(), is_(), is_clause_element, is_distinct_from(), is_selectable, isnot(), isnot_distinct_from(), key, label(), like(), match(), notilike(), notin_(), notlike(), nullsfirst(), nullslast(), op(), operate(), params(), primary_key, proxy_set, reverse_operate(), self_group(), shares_lineage(), startswith(), supports_execution, timetuple, type, unique_params()

Class signature

class sqlalchemy.sql.expression.ColumnElement (sqlalchemy.sql.operators.ColumnOperators, sqlalchemy.sql.expression.ClauseElement)

method sqlalchemy.sql.expression.ColumnElement.__eq__(other)

inherited from the sqlalchemy.sql.operators.ColumnOperators.__eq__ method of ColumnOperators

Implement the == operator.

In a column context, produces the clause a = b. If the target is None, produces a IS NULL.

method sqlalchemy.sql.expression.ColumnElement.__le__(other)

inherited from the sqlalchemy.sql.operators.ColumnOperators.__le__ method of ColumnOperators

Implement the <= operator.

In a column context, produces the clause a <= b.

method sqlalchemy.sql.expression.ColumnElement.__lt__(other)

inherited from the sqlalchemy.sql.operators.ColumnOperators.__lt__ method of ColumnOperators

Implement the < operator.

In a column context, produces the clause a < b.

method sqlalchemy.sql.expression.ColumnElement.__ne__(other)

inherited from the sqlalchemy.sql.operators.ColumnOperators.__ne__ method of ColumnOperators

Implement the != operator.

In a column context, produces the clause a != b. If the target is None, produces a IS NOT NULL.

method sqlalchemy.sql.expression.ColumnElement.all_()

inherited from the ColumnOperators.all_() method of ColumnOperators

Produce a all_() clause against the parent object.

This operator is only appropriate against a scalar subquery object, or for some backends an column expression that is against the ARRAY type, e.g.:

# postgresql '5 = ALL (somearray)'
expr = 5 == mytable.c.somearray.all_()

# mysql '5 = ALL (SELECT value FROM table)'
expr = 5 == select([table.c.value]).as_scalar().all_()

See also

all_() - standalone version

any_() - ANY operator

New in version 1.1.

attribute sqlalchemy.sql.expression.ColumnElement.anon_label

provides a constant ‘anonymous label’ for this ColumnElement.

This is a label() expression which will be named at compile time. The same label() is returned each time anon_label is called so that expressions can reference anon_label multiple times, producing the same label name at compile time.

the compiler uses this function automatically at compile time for expressions that are known to be ‘unnamed’ like binary expressions and function calls.

method sqlalchemy.sql.expression.ColumnElement.any_()

inherited from the ColumnOperators.any_() method of ColumnOperators

Produce a any_() clause against the parent object.

This operator is only appropriate against a scalar subquery object, or for some backends an column expression that is against the ARRAY type, e.g.:

# postgresql '5 = ANY (somearray)'
expr = 5 == mytable.c.somearray.any_()

# mysql '5 = ANY (SELECT value FROM table)'
expr = 5 == select([table.c.value]).as_scalar().any_()

See also

any_() - standalone version

all_() - ALL operator

New in version 1.1.

method sqlalchemy.sql.expression.ColumnElement.asc()

inherited from the ColumnOperators.asc() method of ColumnOperators

Produce a asc() clause against the parent object.

attribute sqlalchemy.sql.expression.ColumnElement.base_columns

method sqlalchemy.sql.expression.ColumnElement.between(cleft, cright, symmetric=False)

inherited from the ColumnOperators.between() method of ColumnOperators

Produce a between() clause against the parent object, given the lower and upper range.

attribute sqlalchemy.sql.expression.ColumnElement.bind = None

method sqlalchemy.sql.expression.ColumnElement.bool_op(opstring, precedence=0)

inherited from the Operators.bool_op() method of Operators

Return a custom boolean operator.

This method is shorthand for calling Operators.op() and passing the Operators.op.is_comparison flag with True.

New in version 1.2.0b3.

See also

Operators.op()

method sqlalchemy.sql.expression.ColumnElement.cast(type_)

Produce a type cast, i.e. CAST(<expression> AS <type>).

This is a shortcut to the cast() function.

New in version 1.0.7.

method sqlalchemy.sql.expression.ColumnElement.collate(collation)

inherited from the ColumnOperators.collate() method of ColumnOperators

Produce a collate() clause against the parent object, given the collation string.

See also

collate()

attribute sqlalchemy.sql.expression.ColumnElement.comparator

method sqlalchemy.sql.expression.ColumnElement.compare(other, use_proxies=False, equivalents=None, **kw)

Compare this ColumnElement to another.

Special arguments understood:

Parameters:

• use_proxies – when True, consider two columns that share a common base column as equivalent (i.e. shares_lineage())

• equivalents – a dictionary of columns as keys mapped to sets of columns. If the given “other” column is present in this dictionary, if any of the columns in the corresponding set() pass the comparison test, the result is True. This is used to expand the comparison to other columns that may be known to be equivalent to this one via foreign key or other criterion.

method sqlalchemy.sql.expression.ColumnElement.compile(default, bind=None, dialect=None, **kw)

inherited from the ClauseElement.compile() method of ClauseElement

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 Engine or Connection from which a Compiled will be acquired. This argument takes precedence over this ClauseElement’s bound engine, if any.

• 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 from which a Compiled will be acquired. This argument takes precedence over the bind argument as well as this ClauseElement’s bound engine, if any.

• inline – Used for INSERT statements, for a dialect which does not support inline retrieval of newly generated primary key columns, will force the expression used to create the new primary key value to be rendered inline within the INSERT statement’s VALUES clause. This typically refers to Sequence execution but may also refer to any server-side default generation function associated with a primary key Column.

• 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})

  New in version 0.9.0.

See also

How do I render SQL expressions as strings, possibly with bound parameters inlined?

method sqlalchemy.sql.expression.ColumnElement.concat(other)

inherited from the ColumnOperators.concat() method of ColumnOperators

Implement the ‘concat’ operator.

In a column context, produces the clause a || b, or uses the concat() operator on MySQL.

method sqlalchemy.sql.expression.ColumnElement.contains(other, **kwargs)

inherited from the ColumnOperators.contains() method of ColumnOperators

Implement the ‘contains’ operator.

Produces a LIKE expression that tests against a match for the middle of a string value:

column LIKE '%' || <other> || '%'

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.contains("foobar"))

Since the operator uses LIKE, wildcard characters "%" and "_" that are present inside the <other> expression will behave like wildcards as well. For literal string values, the ColumnOperators.contains.autoescape flag may be set to True to apply escaping to occurrences of these characters within the string value so that they match as themselves and not as wildcard characters. Alternatively, the ColumnOperators.contains.escape parameter will establish a given character as an escape character which can be of use when the target expression is not a literal string.

Parameters:

• other – expression to be compared. This is usually a plain string value, but can also be an arbitrary SQL expression. LIKE wildcard characters % and _ are not escaped by default unless the ColumnOperators.contains.autoescape flag is set to True.

• autoescape –

  boolean; when True, establishes an escape character within the LIKE expression, then applies it to all occurrences of "%", "_" and the escape character itself within the comparison value, which is assumed to be a literal string and not a SQL expression.

  An expression such as:

  somecolumn.contains("foo%bar", autoescape=True)

  Will render as:

  somecolumn LIKE '%' || :param || '%' ESCAPE '/'

  With the value of :param as "foo/%bar".

  New in version 1.2.

  Changed in version 1.2.0: The ColumnOperators.contains.autoescape parameter is now a simple boolean rather than a character; the escape character itself is also escaped, and defaults to a forwards slash, which itself can be customized using the ColumnOperators.contains.escape parameter.

• escape –

  a character which when given will render with the ESCAPE keyword to establish that character as the escape character. This character can then be placed preceding occurrences of % and _ to allow them to act as themselves and not wildcard characters.

  An expression such as:

  somecolumn.contains("foo/%bar", escape="^")

  Will render as:

  somecolumn LIKE '%' || :param || '%' ESCAPE '^'

  The parameter may also be combined with ColumnOperators.contains.autoescape:

  somecolumn.contains("foo%bar^bat", escape="^", autoescape=True)

  Where above, the given literal parameter will be converted to "foo^%bar^^bat" before being passed to the database.

See also

ColumnOperators.startswith()

ColumnOperators.endswith()

ColumnOperators.like()

method sqlalchemy.sql.expression.ColumnElement.desc()

inherited from the ColumnOperators.desc() method of ColumnOperators

Produce a desc() clause against the parent object.

attribute sqlalchemy.sql.expression.ColumnElement.description = None

method sqlalchemy.sql.expression.ColumnElement.distinct()

inherited from the ColumnOperators.distinct() method of ColumnOperators

Produce a distinct() clause against the parent object.

method sqlalchemy.sql.expression.ColumnElement.endswith(other, **kwargs)

inherited from the ColumnOperators.endswith() method of ColumnOperators

Implement the ‘endswith’ operator.

Produces a LIKE expression that tests against a match for the end of a string value:

column LIKE '%' || <other>

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.endswith("foobar"))

Since the operator uses LIKE, wildcard characters "%" and "_" that are present inside the <other> expression will behave like wildcards as well. For literal string values, the ColumnOperators.endswith.autoescape flag may be set to True to apply escaping to occurrences of these characters within the string value so that they match as themselves and not as wildcard characters. Alternatively, the ColumnOperators.endswith.escape parameter will establish a given character as an escape character which can be of use when the target expression is not a literal string.

Parameters:

• other – expression to be compared. This is usually a plain string value, but can also be an arbitrary SQL expression. LIKE wildcard characters % and _ are not escaped by default unless the ColumnOperators.endswith.autoescape flag is set to True.

• autoescape –

  boolean; when True, establishes an escape character within the LIKE expression, then applies it to all occurrences of "%", "_" and the escape character itself within the comparison value, which is assumed to be a literal string and not a SQL expression.

  An expression such as:

  somecolumn.endswith("foo%bar", autoescape=True)

  Will render as:

  somecolumn LIKE '%' || :param ESCAPE '/'

  With the value of :param as "foo/%bar".

  New in version 1.2.

  Changed in version 1.2.0: The ColumnOperators.endswith.autoescape parameter is now a simple boolean rather than a character; the escape character itself is also escaped, and defaults to a forwards slash, which itself can be customized using the ColumnOperators.endswith.escape parameter.

• escape –

  a character which when given will render with the ESCAPE keyword to establish that character as the escape character. This character can then be placed preceding occurrences of % and _ to allow them to act as themselves and not wildcard characters.

  An expression such as:

  somecolumn.endswith("foo/%bar", escape="^")

  Will render as:

  somecolumn LIKE '%' || :param ESCAPE '^'

  The parameter may also be combined with ColumnOperators.endswith.autoescape:

  somecolumn.endswith("foo%bar^bat", escape="^", autoescape=True)

  Where above, the given literal parameter will be converted to "foo^%bar^^bat" before being passed to the database.

See also

ColumnOperators.startswith()

ColumnOperators.contains()

ColumnOperators.like()

attribute sqlalchemy.sql.expression.ColumnElement.expression

Return a column expression.

Part of the inspection interface; returns self.

attribute sqlalchemy.sql.expression.ColumnElement.foreign_keys = []

method sqlalchemy.sql.expression.ColumnElement.get_children(**kwargs)

inherited from the ClauseElement.get_children() method of ClauseElement

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs 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.ColumnElement.ilike(other, escape=None)

inherited from the ColumnOperators.ilike() method of ColumnOperators

Implement the ilike operator, e.g. case insensitive LIKE.

In a column context, produces an expression either of the form:

lower(a) LIKE lower(other)

Or on backends that support the ILIKE operator:

a ILIKE other

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.ilike("%foobar%"))

Parameters:

• other – expression to be compared

• escape –

  optional escape character, renders the ESCAPE keyword, e.g.:

  somecolumn.ilike("foo/%bar", escape="/")

See also

ColumnOperators.like()

method sqlalchemy.sql.expression.ColumnElement.in_(other)

inherited from the ColumnOperators.in_() method of ColumnOperators

Implement the in operator.

In a column context, produces the clause column IN <other>.

The given parameter other may be:

• A list of literal values, e.g.:

  stmt.where(column.in_([1, 2, 3]))

  In this calling form, the list of items is converted to a set of bound parameters the same length as the list given:

  WHERE COL IN (?, ?, ?)

• An empty list, e.g.:

  stmt.where(column.in_([]))

  In this calling form, the expression renders a “false” expression, e.g.:

  WHERE 1 != 1

  This “false” expression has historically had different behaviors in older SQLAlchemy versions, see create_engine.empty_in_strategy for behavioral options.

  Changed in version 1.2: simplified the behavior of “empty in” expressions

• A bound parameter, e.g. bindparam(), may be used if it includes the bindparam.expanding flag:

  stmt.where(column.in_(bindparam('value', expanding=True)))

  In this calling form, the expression renders a special non-SQL placeholder expression that looks like:

  WHERE COL IN ([EXPANDING_value])

  This placeholder expression is intercepted at statement execution time to be converted into the variable number of bound parameter form illustrated earlier. If the statement were executed as:

  connection.execute(stmt, {"value": [1, 2, 3]})

  The database would be passed a bound parameter for each value:

  WHERE COL IN (?, ?, ?)

  New in version 1.2: added “expanding” bound parameters

  The “expanding” feature in version 1.2 of SQLAlchemy does not support passing an empty list as a parameter value; however, version 1.3 does support this.

• a select() construct, which is usually a correlated scalar select:

  stmt.where(
      column.in_(
          select([othertable.c.y]).
          where(table.c.x == othertable.c.x)
      )
  )

  In this calling form, ColumnOperators.in_() renders as given:

  WHERE COL IN (SELECT othertable.y
  FROM othertable WHERE othertable.x = table.x)

Parameters:

other – a list of literals, a select() construct, or a bindparam() construct that includes the bindparam.expanding flag set to True.

method sqlalchemy.sql.expression.ColumnElement.is_(other)

inherited from the ColumnOperators.is_() method of ColumnOperators

Implement the IS operator.

Normally, IS is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS may be desirable if comparing to boolean values on certain platforms.

See also

ColumnOperators.isnot()

attribute sqlalchemy.sql.expression.ColumnElement.is_clause_element = True

method sqlalchemy.sql.expression.ColumnElement.is_distinct_from(other)

inherited from the ColumnOperators.is_distinct_from() method of ColumnOperators

Implement the IS DISTINCT FROM operator.

Renders “a IS DISTINCT FROM b” on most platforms; on some such as SQLite may render “a IS NOT b”.

New in version 1.1.

attribute sqlalchemy.sql.expression.ColumnElement.is_selectable = False

method sqlalchemy.sql.expression.ColumnElement.isnot(other)

inherited from the ColumnOperators.isnot() method of ColumnOperators

Implement the IS NOT operator.

Normally, IS NOT is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS NOT may be desirable if comparing to boolean values on certain platforms.

See also

ColumnOperators.is_()

method sqlalchemy.sql.expression.ColumnElement.isnot_distinct_from(other)

inherited from the ColumnOperators.isnot_distinct_from() method of ColumnOperators

Implement the IS NOT DISTINCT FROM operator.

Renders “a IS NOT DISTINCT FROM b” on most platforms; on some such as SQLite may render “a IS b”.

New in version 1.1.

attribute sqlalchemy.sql.expression.ColumnElement.key = None

the ‘key’ that in some circumstances refers to this object in a Python namespace.

This typically refers to the “key” of the column as present in the .c collection of a selectable, e.g. sometable.c[“somekey”] would return a Column with a .key of “somekey”.

method sqlalchemy.sql.expression.ColumnElement.label(name)

Produce a column label, i.e. <columnname> AS <name>.

This is a shortcut to the label() function.

if ‘name’ is None, an anonymous label name will be generated.

method sqlalchemy.sql.expression.ColumnElement.like(other, escape=None)

inherited from the ColumnOperators.like() method of ColumnOperators

Implement the like operator.

In a column context, produces the expression:

a LIKE other

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.like("%foobar%"))

Parameters:

• other – expression to be compared

• escape –

  optional escape character, renders the ESCAPE keyword, e.g.:

  somecolumn.like("foo/%bar", escape="/")

See also

ColumnOperators.ilike()

method sqlalchemy.sql.expression.ColumnElement.match(other, **kwargs)

inherited from the ColumnOperators.match() method of ColumnOperators

Implements a database-specific ‘match’ operator.

ColumnOperators.match() attempts to resolve to a MATCH-like function or operator provided by the backend. Examples include:

• PostgreSQL - renders x @@ to_tsquery(y)

• MySQL - renders MATCH (x) AGAINST (y IN BOOLEAN MODE)

• Oracle - renders CONTAINS(x, y)

• other backends may provide special implementations.

• Backends without any special implementation will emit the operator as “MATCH”. This is compatible with SQLite, for example.

method sqlalchemy.sql.expression.ColumnElement.notilike(other, escape=None)

inherited from the ColumnOperators.notilike() method of ColumnOperators

implement the NOT ILIKE operator.

This is equivalent to using negation with ColumnOperators.ilike(), i.e. ~x.ilike(y).

See also

ColumnOperators.ilike()

method sqlalchemy.sql.expression.ColumnElement.notin_(other)

inherited from the ColumnOperators.notin_() method of ColumnOperators

implement the NOT IN operator.

This is equivalent to using negation with ColumnOperators.in_(), i.e. ~x.in_(y).

In the case that other is an empty sequence, the compiler produces an “empty not in” expression. This defaults to the expression “1 = 1” to produce true in all cases. The create_engine.empty_in_strategy may be used to alter this behavior.

Changed in version 1.2: The ColumnOperators.in_() and ColumnOperators.notin_() operators now produce a “static” expression for an empty IN sequence by default.

See also

ColumnOperators.in_()

method sqlalchemy.sql.expression.ColumnElement.notlike(other, escape=None)

inherited from the ColumnOperators.notlike() method of ColumnOperators

implement the NOT LIKE operator.

This is equivalent to using negation with ColumnOperators.like(), i.e. ~x.like(y).

See also

ColumnOperators.like()

method sqlalchemy.sql.expression.ColumnElement.nullsfirst()

inherited from the ColumnOperators.nullsfirst() method of ColumnOperators

Produce a nullsfirst() clause against the parent object.

method sqlalchemy.sql.expression.ColumnElement.nullslast()

inherited from the ColumnOperators.nullslast() method of ColumnOperators

Produce a nullslast() clause against the parent object.

method sqlalchemy.sql.expression.ColumnElement.op(opstring, precedence=0, is_comparison=False, return_type=None)

inherited from the Operators.op() method of Operators

produce a generic operator function.

e.g.:

somecolumn.op("*")(5)

produces:

somecolumn * 5

This function can also be used to make bitwise operators explicit. For example:

somecolumn.op('&')(0xff)

is a bitwise AND of the value in somecolumn.

Parameters:

• operator – a string which will be output as the infix operator between this element and the expression passed to the generated function.

• precedence – precedence to apply to the operator, when parenthesizing expressions. A lower number will cause the expression to be parenthesized when applied against another operator with higher precedence. The default value of 0 is lower than all operators except for the comma (,) and AS operators. A value of 100 will be higher or equal to all operators, and -100 will be lower than or equal to all operators.

• is_comparison –

  if True, the operator will be considered as a “comparison” operator, that is which evaluates to a boolean true/false value, like ==, >, etc. This flag should be set so that ORM relationships can establish that the operator is a comparison operator when used in a custom join condition.

  New in version 0.9.2: - added the Operators.op.is_comparison flag.

• return_type –

  a TypeEngine class or object that will force the return type of an expression produced by this operator to be of that type. By default, operators that specify Operators.op.is_comparison will resolve to Boolean, and those that do not will be of the same type as the left-hand operand.

  New in version 1.2.0b3: - added the Operators.op.return_type argument.

See also

Redefining and Creating New Operators

Using custom operators in join conditions

method sqlalchemy.sql.expression.ColumnElement.operate(op, *other, **kwargs)

Operate on an argument.

This is the lowest level of operation, raises NotImplementedError by default.

Overriding this on a subclass can allow common behavior to be applied to all operations. For example, overriding ColumnOperators to apply func.lower() to the left and right side:

class MyComparator(ColumnOperators):
    def operate(self, op, other):
        return op(func.lower(self), func.lower(other))

Parameters:

• op – Operator callable.

• *other – the ‘other’ side of the operation. Will be a single scalar for most operations.

• **kwargs – modifiers. These may be passed by special operators such as ColumnOperators.contains().

method sqlalchemy.sql.expression.ColumnElement.params(*optionaldict, **kwargs)

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}

attribute sqlalchemy.sql.expression.ColumnElement.primary_key = False

attribute sqlalchemy.sql.expression.ColumnElement.proxy_set

method sqlalchemy.sql.expression.ColumnElement.reverse_operate(op, other, **kwargs)

Reverse operate on an argument.

Usage is the same as operate().

method sqlalchemy.sql.expression.ColumnElement.self_group(against=None)

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.ColumnElement.shares_lineage(othercolumn)

Return True if the given ColumnElement has a common ancestor to this ColumnElement.

method sqlalchemy.sql.expression.ColumnElement.startswith(other, **kwargs)

inherited from the ColumnOperators.startswith() method of ColumnOperators

Implement the startswith operator.

Produces a LIKE expression that tests against a match for the start of a string value:

column LIKE <other> || '%'

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.startswith("foobar"))

Since the operator uses LIKE, wildcard characters "%" and "_" that are present inside the <other> expression will behave like wildcards as well. For literal string values, the ColumnOperators.startswith.autoescape flag may be set to True to apply escaping to occurrences of these characters within the string value so that they match as themselves and not as wildcard characters. Alternatively, the ColumnOperators.startswith.escape parameter will establish a given character as an escape character which can be of use when the target expression is not a literal string.

Parameters:

• other – expression to be compared. This is usually a plain string value, but can also be an arbitrary SQL expression. LIKE wildcard characters % and _ are not escaped by default unless the ColumnOperators.startswith.autoescape flag is set to True.

• autoescape –

  boolean; when True, establishes an escape character within the LIKE expression, then applies it to all occurrences of "%", "_" and the escape character itself within the comparison value, which is assumed to be a literal string and not a SQL expression.

  An expression such as:

  somecolumn.startswith("foo%bar", autoescape=True)

  Will render as:

  somecolumn LIKE :param || '%' ESCAPE '/'

  With the value of :param as "foo/%bar".

  New in version 1.2.

  Changed in version 1.2.0: The ColumnOperators.startswith.autoescape parameter is now a simple boolean rather than a character; the escape character itself is also escaped, and defaults to a forwards slash, which itself can be customized using the ColumnOperators.startswith.escape parameter.

• escape –

  a character which when given will render with the ESCAPE keyword to establish that character as the escape character. This character can then be placed preceding occurrences of % and _ to allow them to act as themselves and not wildcard characters.

  An expression such as:

  somecolumn.startswith("foo/%bar", escape="^")

  Will render as:

  somecolumn LIKE :param || '%' ESCAPE '^'

  The parameter may also be combined with ColumnOperators.startswith.autoescape:

  somecolumn.startswith("foo%bar^bat", escape="^", autoescape=True)

  Where above, the given literal parameter will be converted to "foo^%bar^^bat" before being passed to the database.

See also

ColumnOperators.endswith()

ColumnOperators.contains()

ColumnOperators.like()

attribute sqlalchemy.sql.expression.ColumnElement.supports_execution = False

attribute sqlalchemy.sql.expression.ColumnElement.timetuple = None

inherited from the ColumnOperators.timetuple attribute of ColumnOperators

Hack, allows datetime objects to be compared on the LHS.

attribute sqlalchemy.sql.expression.ColumnElement.type

method sqlalchemy.sql.expression.ColumnElement.unique_params(*optionaldict, **kwargs)

inherited from the ClauseElement.unique_params() method of ClauseElement

Return a copy with bindparam() elements replaced.

Same functionality as params(), except adds unique=True to affected bind parameters so that multiple statements can be used.

class sqlalchemy.sql.operators.ColumnOperators

Defines boolean, comparison, and other operators for ColumnElement expressions.

By default, all methods call down to operate() or reverse_operate(), passing in the appropriate operator function from the Python builtin operator module or a SQLAlchemy-specific operator function from sqlalchemy.expression.operators. For example the __eq__ function:

def __eq__(self, other):
    return self.operate(operators.eq, other)

Where operators.eq is essentially:

def eq(a, b):
    return a == b

The core column expression unit ColumnElement overrides Operators.operate() and others to return further ColumnElement constructs, so that the == operation above is replaced by a clause construct.

See also

Redefining and Creating New Operators

TypeEngine.comparator_factory

ColumnOperators

PropComparator

Members

__add__(), __and__(), __div__(), __eq__(), __ge__(), __getitem__(), __gt__(), __hash__(), __invert__(), __le__(), __lshift__(), __lt__(), __mod__(), __mul__(), __ne__(), __neg__(), __or__(), __radd__(), __rdiv__(), __rmod__(), __rmul__(), __rshift__(), __rsub__(), __rtruediv__(), __sub__(), __truediv__(), all_(), any_(), asc(), between(), bool_op(), collate(), concat(), contains(), desc(), distinct(), endswith(), ilike(), in_(), is_(), is_distinct_from(), isnot(), isnot_distinct_from(), like(), match(), notilike(), notin_(), notlike(), nullsfirst(), nullslast(), op(), operate(), reverse_operate(), startswith(), timetuple

Class signature

class sqlalchemy.sql.operators.ColumnOperators (sqlalchemy.sql.operators.Operators)

method sqlalchemy.sql.operators.ColumnOperators.__add__(other)

Implement the + operator.

In a column context, produces the clause a + b if the parent object has non-string affinity. If the parent object has a string affinity, produces the concatenation operator, a || b - see ColumnOperators.concat().

method sqlalchemy.sql.operators.ColumnOperators.__and__(other)

inherited from the sqlalchemy.sql.operators.Operators.__and__ method of Operators

Implement the & operator.

When used with SQL expressions, results in an AND operation, equivalent to and_(), that is:

a & b

is equivalent to:

from sqlalchemy import and_
and_(a, b)

Care should be taken when using & regarding operator precedence; the & operator has the highest precedence. The operands should be enclosed in parenthesis if they contain further sub expressions:

(a == 2) & (b == 4)

method sqlalchemy.sql.operators.ColumnOperators.__div__(other)

Implement the / operator.

In a column context, produces the clause a / b.

method sqlalchemy.sql.operators.ColumnOperators.__eq__(other)

Implement the == operator.

In a column context, produces the clause a = b. If the target is None, produces a IS NULL.

method sqlalchemy.sql.operators.ColumnOperators.__ge__(other)

Implement the >= operator.

In a column context, produces the clause a >= b.

method sqlalchemy.sql.operators.ColumnOperators.__getitem__(index)

Implement the [] operator.

This can be used by some database-specific types such as PostgreSQL ARRAY and HSTORE.

method sqlalchemy.sql.operators.ColumnOperators.__gt__(other)

Implement the > operator.

In a column context, produces the clause a > b.

method sqlalchemy.sql.operators.ColumnOperators.__hash__()

Return hash(self).

method sqlalchemy.sql.operators.ColumnOperators.__invert__()

inherited from the sqlalchemy.sql.operators.Operators.__invert__ method of Operators

Implement the ~ operator.

When used with SQL expressions, results in a NOT operation, equivalent to not_(), that is:

~a

is equivalent to:

from sqlalchemy import not_
not_(a)

method sqlalchemy.sql.operators.ColumnOperators.__le__(other)

Implement the <= operator.

In a column context, produces the clause a <= b.

method sqlalchemy.sql.operators.ColumnOperators.__lshift__(other)

implement the << operator.

Not used by SQLAlchemy core, this is provided for custom operator systems which want to use << as an extension point.

method sqlalchemy.sql.operators.ColumnOperators.__lt__(other)

Implement the < operator.

In a column context, produces the clause a < b.

method sqlalchemy.sql.operators.ColumnOperators.__mod__(other)

Implement the % operator.

In a column context, produces the clause a % b.

method sqlalchemy.sql.operators.ColumnOperators.__mul__(other)

Implement the * operator.

In a column context, produces the clause a * b.

method sqlalchemy.sql.operators.ColumnOperators.__ne__(other)

Implement the != operator.

In a column context, produces the clause a != b. If the target is None, produces a IS NOT NULL.

method sqlalchemy.sql.operators.ColumnOperators.__neg__()

Implement the - operator.

In a column context, produces the clause -a.

method sqlalchemy.sql.operators.ColumnOperators.__or__(other)

inherited from the sqlalchemy.sql.operators.Operators.__or__ method of Operators

Implement the | operator.

When used with SQL expressions, results in an OR operation, equivalent to or_(), that is:

a | b

is equivalent to:

from sqlalchemy import or_
or_(a, b)

Care should be taken when using | regarding operator precedence; the | operator has the highest precedence. The operands should be enclosed in parenthesis if they contain further sub expressions:

(a == 2) | (b == 4)

method sqlalchemy.sql.operators.ColumnOperators.__radd__(other)

Implement the + operator in reverse.

See ColumnOperators.__add__().

method sqlalchemy.sql.operators.ColumnOperators.__rdiv__(other)

Implement the / operator in reverse.

See ColumnOperators.__div__().

method sqlalchemy.sql.operators.ColumnOperators.__rmod__(other)

Implement the % operator in reverse.

See ColumnOperators.__mod__().

method sqlalchemy.sql.operators.ColumnOperators.__rmul__(other)

Implement the * operator in reverse.

See ColumnOperators.__mul__().

method sqlalchemy.sql.operators.ColumnOperators.__rshift__(other)

implement the >> operator.

Not used by SQLAlchemy core, this is provided for custom operator systems which want to use >> as an extension point.

method sqlalchemy.sql.operators.ColumnOperators.__rsub__(other)

Implement the - operator in reverse.

See ColumnOperators.__sub__().

method sqlalchemy.sql.operators.ColumnOperators.__rtruediv__(other)

Implement the // operator in reverse.

See ColumnOperators.__truediv__().

method sqlalchemy.sql.operators.ColumnOperators.__sub__(other)

Implement the - operator.

In a column context, produces the clause a - b.

method sqlalchemy.sql.operators.ColumnOperators.__truediv__(other)

Implement the // operator.

In a column context, produces the clause a / b.

method sqlalchemy.sql.operators.ColumnOperators.all_()

Produce a all_() clause against the parent object.

This operator is only appropriate against a scalar subquery object, or for some backends an column expression that is against the ARRAY type, e.g.:

# postgresql '5 = ALL (somearray)'
expr = 5 == mytable.c.somearray.all_()

# mysql '5 = ALL (SELECT value FROM table)'
expr = 5 == select([table.c.value]).as_scalar().all_()

See also

all_() - standalone version

any_() - ANY operator

New in version 1.1.

method sqlalchemy.sql.operators.ColumnOperators.any_()

Produce a any_() clause against the parent object.

This operator is only appropriate against a scalar subquery object, or for some backends an column expression that is against the ARRAY type, e.g.:

# postgresql '5 = ANY (somearray)'
expr = 5 == mytable.c.somearray.any_()

# mysql '5 = ANY (SELECT value FROM table)'
expr = 5 == select([table.c.value]).as_scalar().any_()

See also

any_() - standalone version

all_() - ALL operator

New in version 1.1.

method sqlalchemy.sql.operators.ColumnOperators.asc()

Produce a asc() clause against the parent object.

method sqlalchemy.sql.operators.ColumnOperators.between(cleft, cright, symmetric=False)

Produce a between() clause against the parent object, given the lower and upper range.

method sqlalchemy.sql.operators.ColumnOperators.bool_op(opstring, precedence=0)

inherited from the Operators.bool_op() method of Operators

Return a custom boolean operator.

This method is shorthand for calling Operators.op() and passing the Operators.op.is_comparison flag with True.

New in version 1.2.0b3.

See also

Operators.op()

method sqlalchemy.sql.operators.ColumnOperators.collate(collation)

Produce a collate() clause against the parent object, given the collation string.

See also

collate()

method sqlalchemy.sql.operators.ColumnOperators.concat(other)

Implement the ‘concat’ operator.

In a column context, produces the clause a || b, or uses the concat() operator on MySQL.

method sqlalchemy.sql.operators.ColumnOperators.contains(other, **kwargs)

Implement the ‘contains’ operator.

Produces a LIKE expression that tests against a match for the middle of a string value:

column LIKE '%' || <other> || '%'

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.contains("foobar"))

Since the operator uses LIKE, wildcard characters "%" and "_" that are present inside the <other> expression will behave like wildcards as well. For literal string values, the ColumnOperators.contains.autoescape flag may be set to True to apply escaping to occurrences of these characters within the string value so that they match as themselves and not as wildcard characters. Alternatively, the ColumnOperators.contains.escape parameter will establish a given character as an escape character which can be of use when the target expression is not a literal string.

Parameters:

• other – expression to be compared. This is usually a plain string value, but can also be an arbitrary SQL expression. LIKE wildcard characters % and _ are not escaped by default unless the ColumnOperators.contains.autoescape flag is set to True.

• autoescape –

  boolean; when True, establishes an escape character within the LIKE expression, then applies it to all occurrences of "%", "_" and the escape character itself within the comparison value, which is assumed to be a literal string and not a SQL expression.

  An expression such as:

  somecolumn.contains("foo%bar", autoescape=True)

  Will render as:

  somecolumn LIKE '%' || :param || '%' ESCAPE '/'

  With the value of :param as "foo/%bar".

  New in version 1.2.

  Changed in version 1.2.0: The ColumnOperators.contains.autoescape parameter is now a simple boolean rather than a character; the escape character itself is also escaped, and defaults to a forwards slash, which itself can be customized using the ColumnOperators.contains.escape parameter.

• escape –

  a character which when given will render with the ESCAPE keyword to establish that character as the escape character. This character can then be placed preceding occurrences of % and _ to allow them to act as themselves and not wildcard characters.

  An expression such as:

  somecolumn.contains("foo/%bar", escape="^")

  Will render as:

  somecolumn LIKE '%' || :param || '%' ESCAPE '^'

  The parameter may also be combined with ColumnOperators.contains.autoescape:

  somecolumn.contains("foo%bar^bat", escape="^", autoescape=True)

  Where above, the given literal parameter will be converted to "foo^%bar^^bat" before being passed to the database.

See also

ColumnOperators.startswith()

ColumnOperators.endswith()

ColumnOperators.like()

method sqlalchemy.sql.operators.ColumnOperators.desc()

Produce a desc() clause against the parent object.

method sqlalchemy.sql.operators.ColumnOperators.distinct()

Produce a distinct() clause against the parent object.

method sqlalchemy.sql.operators.ColumnOperators.endswith(other, **kwargs)

Implement the ‘endswith’ operator.

Produces a LIKE expression that tests against a match for the end of a string value:

column LIKE '%' || <other>

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.endswith("foobar"))

Since the operator uses LIKE, wildcard characters "%" and "_" that are present inside the <other> expression will behave like wildcards as well. For literal string values, the ColumnOperators.endswith.autoescape flag may be set to True to apply escaping to occurrences of these characters within the string value so that they match as themselves and not as wildcard characters. Alternatively, the ColumnOperators.endswith.escape parameter will establish a given character as an escape character which can be of use when the target expression is not a literal string.

Parameters:

• other – expression to be compared. This is usually a plain string value, but can also be an arbitrary SQL expression. LIKE wildcard characters % and _ are not escaped by default unless the ColumnOperators.endswith.autoescape flag is set to True.

• autoescape –

  boolean; when True, establishes an escape character within the LIKE expression, then applies it to all occurrences of "%", "_" and the escape character itself within the comparison value, which is assumed to be a literal string and not a SQL expression.

  An expression such as:

  somecolumn.endswith("foo%bar", autoescape=True)

  Will render as:

  somecolumn LIKE '%' || :param ESCAPE '/'

  With the value of :param as "foo/%bar".

  New in version 1.2.

  Changed in version 1.2.0: The ColumnOperators.endswith.autoescape parameter is now a simple boolean rather than a character; the escape character itself is also escaped, and defaults to a forwards slash, which itself can be customized using the ColumnOperators.endswith.escape parameter.

• escape –

  a character which when given will render with the ESCAPE keyword to establish that character as the escape character. This character can then be placed preceding occurrences of % and _ to allow them to act as themselves and not wildcard characters.

  An expression such as:

  somecolumn.endswith("foo/%bar", escape="^")

  Will render as:

  somecolumn LIKE '%' || :param ESCAPE '^'

  The parameter may also be combined with ColumnOperators.endswith.autoescape:

  somecolumn.endswith("foo%bar^bat", escape="^", autoescape=True)

  Where above, the given literal parameter will be converted to "foo^%bar^^bat" before being passed to the database.

See also

ColumnOperators.startswith()

ColumnOperators.contains()

ColumnOperators.like()

method sqlalchemy.sql.operators.ColumnOperators.ilike(other, escape=None)

Implement the ilike operator, e.g. case insensitive LIKE.

In a column context, produces an expression either of the form:

lower(a) LIKE lower(other)

Or on backends that support the ILIKE operator:

a ILIKE other

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.ilike("%foobar%"))

Parameters:

• other – expression to be compared

• escape –

  optional escape character, renders the ESCAPE keyword, e.g.:

  somecolumn.ilike("foo/%bar", escape="/")

See also

ColumnOperators.like()

method sqlalchemy.sql.operators.ColumnOperators.in_(other)

Implement the in operator.

In a column context, produces the clause column IN <other>.

The given parameter other may be:

• A list of literal values, e.g.:

  stmt.where(column.in_([1, 2, 3]))

  In this calling form, the list of items is converted to a set of bound parameters the same length as the list given:

  WHERE COL IN (?, ?, ?)

• An empty list, e.g.:

  stmt.where(column.in_([]))

  In this calling form, the expression renders a “false” expression, e.g.:

  WHERE 1 != 1

  This “false” expression has historically had different behaviors in older SQLAlchemy versions, see create_engine.empty_in_strategy for behavioral options.

  Changed in version 1.2: simplified the behavior of “empty in” expressions

• A bound parameter, e.g. bindparam(), may be used if it includes the bindparam.expanding flag:

  stmt.where(column.in_(bindparam('value', expanding=True)))

  In this calling form, the expression renders a special non-SQL placeholder expression that looks like:

  WHERE COL IN ([EXPANDING_value])

  This placeholder expression is intercepted at statement execution time to be converted into the variable number of bound parameter form illustrated earlier. If the statement were executed as:

  connection.execute(stmt, {"value": [1, 2, 3]})

  The database would be passed a bound parameter for each value:

  WHERE COL IN (?, ?, ?)

  New in version 1.2: added “expanding” bound parameters

  The “expanding” feature in version 1.2 of SQLAlchemy does not support passing an empty list as a parameter value; however, version 1.3 does support this.

• a select() construct, which is usually a correlated scalar select:

  stmt.where(
      column.in_(
          select([othertable.c.y]).
          where(table.c.x == othertable.c.x)
      )
  )

  In this calling form, ColumnOperators.in_() renders as given:

  WHERE COL IN (SELECT othertable.y
  FROM othertable WHERE othertable.x = table.x)

Parameters:

other – a list of literals, a select() construct, or a bindparam() construct that includes the bindparam.expanding flag set to True.

method sqlalchemy.sql.operators.ColumnOperators.is_(other)

Implement the IS operator.

Normally, IS is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS may be desirable if comparing to boolean values on certain platforms.

See also

ColumnOperators.isnot()

method sqlalchemy.sql.operators.ColumnOperators.is_distinct_from(other)

Implement the IS DISTINCT FROM operator.

Renders “a IS DISTINCT FROM b” on most platforms; on some such as SQLite may render “a IS NOT b”.

New in version 1.1.

method sqlalchemy.sql.operators.ColumnOperators.isnot(other)

Implement the IS NOT operator.

Normally, IS NOT is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS NOT may be desirable if comparing to boolean values on certain platforms.

See also

ColumnOperators.is_()

method sqlalchemy.sql.operators.ColumnOperators.isnot_distinct_from(other)

Implement the IS NOT DISTINCT FROM operator.

Renders “a IS NOT DISTINCT FROM b” on most platforms; on some such as SQLite may render “a IS b”.

New in version 1.1.

method sqlalchemy.sql.operators.ColumnOperators.like(other, escape=None)

Implement the like operator.

In a column context, produces the expression:

a LIKE other

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.like("%foobar%"))

Parameters:

• other – expression to be compared

• escape –

  optional escape character, renders the ESCAPE keyword, e.g.:

  somecolumn.like("foo/%bar", escape="/")

See also

ColumnOperators.ilike()

method sqlalchemy.sql.operators.ColumnOperators.match(other, **kwargs)

Implements a database-specific ‘match’ operator.

ColumnOperators.match() attempts to resolve to a MATCH-like function or operator provided by the backend. Examples include:

• PostgreSQL - renders x @@ to_tsquery(y)

• MySQL - renders MATCH (x) AGAINST (y IN BOOLEAN MODE)

• Oracle - renders CONTAINS(x, y)

• other backends may provide special implementations.

• Backends without any special implementation will emit the operator as “MATCH”. This is compatible with SQLite, for example.

method sqlalchemy.sql.operators.ColumnOperators.notilike(other, escape=None)

implement the NOT ILIKE operator.

This is equivalent to using negation with ColumnOperators.ilike(), i.e. ~x.ilike(y).

See also

ColumnOperators.ilike()

method sqlalchemy.sql.operators.ColumnOperators.notin_(other)

implement the NOT IN operator.

This is equivalent to using negation with ColumnOperators.in_(), i.e. ~x.in_(y).

In the case that other is an empty sequence, the compiler produces an “empty not in” expression. This defaults to the expression “1 = 1” to produce true in all cases. The create_engine.empty_in_strategy may be used to alter this behavior.

Changed in version 1.2: The ColumnOperators.in_() and ColumnOperators.notin_() operators now produce a “static” expression for an empty IN sequence by default.

See also

ColumnOperators.in_()

method sqlalchemy.sql.operators.ColumnOperators.notlike(other, escape=None)

implement the NOT LIKE operator.

This is equivalent to using negation with ColumnOperators.like(), i.e. ~x.like(y).

See also

ColumnOperators.like()

method sqlalchemy.sql.operators.ColumnOperators.nullsfirst()

Produce a nullsfirst() clause against the parent object.

method sqlalchemy.sql.operators.ColumnOperators.nullslast()

Produce a nullslast() clause against the parent object.

method sqlalchemy.sql.operators.ColumnOperators.op(opstring, precedence=0, is_comparison=False, return_type=None)

inherited from the Operators.op() method of Operators

produce a generic operator function.

e.g.:

somecolumn.op("*")(5)

produces:

somecolumn * 5

This function can also be used to make bitwise operators explicit. For example:

somecolumn.op('&')(0xff)

is a bitwise AND of the value in somecolumn.

Parameters:

• operator – a string which will be output as the infix operator between this element and the expression passed to the generated function.

• precedence – precedence to apply to the operator, when parenthesizing expressions. A lower number will cause the expression to be parenthesized when applied against another operator with higher precedence. The default value of 0 is lower than all operators except for the comma (,) and AS operators. A value of 100 will be higher or equal to all operators, and -100 will be lower than or equal to all operators.

• is_comparison –

  if True, the operator will be considered as a “comparison” operator, that is which evaluates to a boolean true/false value, like ==, >, etc. This flag should be set so that ORM relationships can establish that the operator is a comparison operator when used in a custom join condition.

  New in version 0.9.2: - added the Operators.op.is_comparison flag.

• return_type –

  a TypeEngine class or object that will force the return type of an expression produced by this operator to be of that type. By default, operators that specify Operators.op.is_comparison will resolve to Boolean, and those that do not will be of the same type as the left-hand operand.

  New in version 1.2.0b3: - added the Operators.op.return_type argument.

See also

Redefining and Creating New Operators

Using custom operators in join conditions

method sqlalchemy.sql.operators.ColumnOperators.operate(op, *other, **kwargs)

inherited from the Operators.operate() method of Operators

Operate on an argument.

This is the lowest level of operation, raises NotImplementedError by default.

Overriding this on a subclass can allow common behavior to be applied to all operations. For example, overriding ColumnOperators to apply func.lower() to the left and right side:

class MyComparator(ColumnOperators):
    def operate(self, op, other):
        return op(func.lower(self), func.lower(other))

Parameters:

• op – Operator callable.

• *other – the ‘other’ side of the operation. Will be a single scalar for most operations.

• **kwargs – modifiers. These may be passed by special operators such as ColumnOperators.contains().

method sqlalchemy.sql.operators.ColumnOperators.reverse_operate(op, other, **kwargs)

inherited from the Operators.reverse_operate() method of Operators

Reverse operate on an argument.

Usage is the same as operate().

method sqlalchemy.sql.operators.ColumnOperators.startswith(other, **kwargs)

Implement the startswith operator.

Produces a LIKE expression that tests against a match for the start of a string value:

column LIKE <other> || '%'

E.g.:

stmt = select([sometable]).\
    where(sometable.c.column.startswith("foobar"))

Since the operator uses LIKE, wildcard characters "%" and "_" that are present inside the <other> expression will behave like wildcards as well. For literal string values, the ColumnOperators.startswith.autoescape flag may be set to True to apply escaping to occurrences of these characters within the string value so that they match as themselves and not as wildcard characters. Alternatively, the ColumnOperators.startswith.escape parameter will establish a given character as an escape character which can be of use when the target expression is not a literal string.

Parameters:

• other – expression to be compared. This is usually a plain string value, but can also be an arbitrary SQL expression. LIKE wildcard characters % and _ are not escaped by default unless the ColumnOperators.startswith.autoescape flag is set to True.

• autoescape –

  boolean; when True, establishes an escape character within the LIKE expression, then applies it to all occurrences of "%", "_" and the escape character itself within the comparison value, which is assumed to be a literal string and not a SQL expression.

  An expression such as:

  somecolumn.startswith("foo%bar", autoescape=True)

  Will render as:

  somecolumn LIKE :param || '%' ESCAPE '/'

  With the value of :param as "foo/%bar".

  New in version 1.2.

  Changed in version 1.2.0: The ColumnOperators.startswith.autoescape parameter is now a simple boolean rather than a character; the escape character itself is also escaped, and defaults to a forwards slash, which itself can be customized using the ColumnOperators.startswith.escape parameter.

• escape –

  a character which when given will render with the ESCAPE keyword to establish that character as the escape character. This character can then be placed preceding occurrences of % and _ to allow them to act as themselves and not wildcard characters.

  An expression such as:

  somecolumn.startswith("foo/%bar", escape="^")

  Will render as:

  somecolumn LIKE :param || '%' ESCAPE '^'

  The parameter may also be combined with ColumnOperators.startswith.autoescape:

  somecolumn.startswith("foo%bar^bat", escape="^", autoescape=True)

  Where above, the given literal parameter will be converted to "foo^%bar^^bat" before being passed to the database.

See also

ColumnOperators.endswith()

ColumnOperators.contains()

ColumnOperators.like()

attribute sqlalchemy.sql.operators.ColumnOperators.timetuple = None

Hack, allows datetime objects to be compared on the LHS.

class sqlalchemy.sql.base.DialectKWArgs

Establish the ability for a class to have dialect-specific arguments with defaults and constructor validation.

The DialectKWArgs interacts with the DefaultDialect.construct_arguments present on a dialect.

Members

argument_for(), dialect_kwargs, dialect_options, kwargs

See also

DefaultDialect.construct_arguments

classmethod sqlalchemy.sql.base.DialectKWArgs.argument_for(dialect_name, argument_name, default)

Add a new kind of dialect-specific keyword argument for this class.

E.g.:

Index.argument_for("mydialect", "length", None)

some_index = Index('a', 'b', mydialect_length=5)

The DialectKWArgs.argument_for() method is a per-argument way adding extra arguments to the DefaultDialect.construct_arguments dictionary. This dictionary provides a list of argument names accepted by various schema-level constructs on behalf of a dialect.

New dialects should typically specify this dictionary all at once as a data member of the dialect class. The use case for ad-hoc addition of argument names is typically for end-user code that is also using a custom compilation scheme which consumes the additional arguments.

Parameters:

• dialect_name – name of a dialect. The dialect must be locatable, else a NoSuchModuleError is raised. The dialect must also include an existing DefaultDialect.construct_arguments collection, indicating that it participates in the keyword-argument validation and default system, else ArgumentError is raised. If the dialect does not include this collection, then any keyword argument can be specified on behalf of this dialect already. All dialects packaged within SQLAlchemy include this collection, however for third party dialects, support may vary.

• argument_name – name of the parameter.

• default – default value of the parameter.

New in version 0.9.4.

attribute sqlalchemy.sql.base.DialectKWArgs.dialect_kwargs

A collection of keyword arguments specified as dialect-specific options to this construct.

The arguments are present here in their original <dialect>_<kwarg> format. Only arguments that were actually passed are included; unlike the DialectKWArgs.dialect_options collection, which contains all options known by this dialect including defaults.

The collection is also writable; keys are accepted of the form <dialect>_<kwarg> where the value will be assembled into the list of options.

New in version 0.9.2.

Changed in version 0.9.4: The DialectKWArgs.dialect_kwargs collection is now writable.

See also

DialectKWArgs.dialect_options - nested dictionary form

attribute sqlalchemy.sql.base.DialectKWArgs.dialect_options

A collection of keyword arguments specified as dialect-specific options to this construct.

This is a two-level nested registry, keyed to <dialect_name> and <argument_name>. For example, the postgresql_where argument would be locatable as:

arg = my_object.dialect_options['postgresql']['where']

New in version 0.9.2.

See also

DialectKWArgs.dialect_kwargs - flat dictionary form

attribute sqlalchemy.sql.base.DialectKWArgs.kwargs

A synonym for DialectKWArgs.dialect_kwargs.

class sqlalchemy.sql.expression.Extract(field, expr, **kwargs)

Represent a SQL EXTRACT clause, extract(field FROM expr).

Members

__init__(), get_children()

Class signature

class sqlalchemy.sql.expression.Extract (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.Extract.__init__(field, expr, **kwargs)

Construct a new Extract object.

This constructor is mirrored as a public API function; see extract() for a full usage and argument description.

method sqlalchemy.sql.expression.Extract.get_children(**kwargs)

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs 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).

class sqlalchemy.sql.elements.False_

Represent the false keyword, or equivalent, in a SQL statement.

False_ is accessed as a constant via the false() function.

Members

compare()

Class signature

class sqlalchemy.sql.expression.False_ (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.elements.False_.compare(other)

Compare this ColumnElement to another.

Special arguments understood:

Parameters:

• use_proxies – when True, consider two columns that share a common base column as equivalent (i.e. shares_lineage())

• equivalents – a dictionary of columns as keys mapped to sets of columns. If the given “other” column is present in this dictionary, if any of the columns in the corresponding set() pass the comparison test, the result is True. This is used to expand the comparison to other columns that may be known to be equivalent to this one via foreign key or other criterion.

class sqlalchemy.sql.expression.FunctionFilter(func, *criterion)

Represent a function FILTER clause.

This is a special operator against aggregate and window functions, which controls which rows are passed to it. It’s supported only by certain database backends.

Invocation of FunctionFilter is via FunctionElement.filter():

func.count(1).filter(True)

New in version 1.0.0.

See also

FunctionElement.filter()

Members

__init__(), filter(), get_children(), over()

Class signature

class sqlalchemy.sql.expression.FunctionFilter (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.FunctionFilter.__init__(func, *criterion)

Construct a new FunctionFilter object.

This constructor is mirrored as a public API function; see funcfilter() for a full usage and argument description.

method sqlalchemy.sql.expression.FunctionFilter.filter(*criterion)

Produce an additional FILTER against the function.

This method adds additional criteria to the initial criteria set up by FunctionElement.filter().

Multiple criteria are joined together at SQL render time via AND.

method sqlalchemy.sql.expression.FunctionFilter.get_children(**kwargs)

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs 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.FunctionFilter.over(partition_by=None, order_by=None, range_=None, rows=None)

Produce an OVER clause against this filtered function.

Used against aggregate or so-called “window” functions, for database backends that support window functions.

The expression:

func.rank().filter(MyClass.y > 5).over(order_by='x')

is shorthand for:

from sqlalchemy import over, funcfilter
over(funcfilter(func.rank(), MyClass.y > 5), order_by='x')

See over() for a full description.

class sqlalchemy.sql.expression.Label(name, element, type_=None)

Represents a column label (AS).

Represent a label, as typically applied to any column-level element using the AS sql keyword.

Members

__init__(), foreign_keys, get_children(), primary_key, self_group()

Class signature

class sqlalchemy.sql.expression.Label (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.Label.__init__(name, element, type_=None)

Construct a new Label object.

This constructor is mirrored as a public API function; see label() for a full usage and argument description.

attribute sqlalchemy.sql.expression.Label.foreign_keys

method sqlalchemy.sql.expression.Label.get_children(**kwargs)

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs 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.Label.primary_key

method sqlalchemy.sql.expression.Label.self_group(against=None)

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.elements.Null

Represent the NULL keyword in a SQL statement.

Null is accessed as a constant via the null() function.

Members

compare()

Class signature

class sqlalchemy.sql.expression.Null (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.elements.Null.compare(other)

Compare this ColumnElement to another.

Special arguments understood:

Parameters:

• use_proxies – when True, consider two columns that share a common base column as equivalent (i.e. shares_lineage())

• equivalents – a dictionary of columns as keys mapped to sets of columns. If the given “other” column is present in this dictionary, if any of the columns in the corresponding set() pass the comparison test, the result is True. This is used to expand the comparison to other columns that may be known to be equivalent to this one via foreign key or other criterion.

class sqlalchemy.sql.expression.Over(element, partition_by=None, order_by=None, range_=None, rows=None)

Represent an OVER clause.

This is a special operator against a so-called “window” function, as well as any aggregate function, which produces results relative to the result set itself. It’s supported only by certain database backends.

Members

__init__(), element, func, get_children()

Class signature

class sqlalchemy.sql.expression.Over (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.Over.__init__(element, partition_by=None, order_by=None, range_=None, rows=None)

Construct a new Over object.

This constructor is mirrored as a public API function; see over() for a full usage and argument description.

attribute sqlalchemy.sql.expression.Over.element = None

The underlying expression object to which this Over object refers towards.

attribute sqlalchemy.sql.expression.Over.func

the element referred to by this Over clause.

Deprecated since version 1.1: the Over.func member of the Over class is deprecated and will be removed in a future release. Please refer to the Over.element attribute.

method sqlalchemy.sql.expression.Over.get_children(**kwargs)

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs 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).

class sqlalchemy.sql.expression.TextClause(text, bind=None)

Represent a literal SQL text fragment.

E.g.:

from sqlalchemy import text

t = text("SELECT * FROM users")
result = connection.execute(t)

The Text construct is produced using the text() function; see that function for full documentation.

See also

text()

Members

bindparams(), columns(), compare(), get_children(), self_group()

Class signature

class sqlalchemy.sql.expression.TextClause (sqlalchemy.sql.expression.Executable, sqlalchemy.sql.expression.ClauseElement)

method sqlalchemy.sql.expression.TextClause.bindparams(*binds, **names_to_values)

Establish the values and/or types of bound parameters within this TextClause construct.

Given a text construct such as:

from sqlalchemy import text
stmt = text("SELECT id, name FROM user WHERE name=:name "
            "AND timestamp=:timestamp")

the TextClause.bindparams() method can be used to establish the initial value of :name and :timestamp, using simple keyword arguments:

stmt = stmt.bindparams(name='jack',
            timestamp=datetime.datetime(2012, 10, 8, 15, 12, 5))

Where above, new BindParameter objects will be generated with the names name and timestamp, and values of jack and datetime.datetime(2012, 10, 8, 15, 12, 5), respectively. The types will be inferred from the values given, in this case String and DateTime.

When specific typing behavior is needed, the positional *binds argument can be used in which to specify bindparam() constructs directly. These constructs must include at least the key argument, then an optional value and type:

from sqlalchemy import bindparam
stmt = stmt.bindparams(
                bindparam('name', value='jack', type_=String),
                bindparam('timestamp', type_=DateTime)
            )

Above, we specified the type of DateTime for the timestamp bind, and the type of String for the name bind. In the case of name we also set the default value of "jack".

Additional bound parameters can be supplied at statement execution time, e.g.:

result = connection.execute(stmt,
            timestamp=datetime.datetime(2012, 10, 8, 15, 12, 5))

The TextClause.bindparams() method can be called repeatedly, where it will re-use existing BindParameter objects to add new information. For example, we can call TextClause.bindparams() first with typing information, and a second time with value information, and it will be combined:

stmt = text("SELECT id, name FROM user WHERE name=:name "
            "AND timestamp=:timestamp")
stmt = stmt.bindparams(
    bindparam('name', type_=String),
    bindparam('timestamp', type_=DateTime)
)
stmt = stmt.bindparams(
    name='jack',
    timestamp=datetime.datetime(2012, 10, 8, 15, 12, 5)
)

New in version 0.9.0: The TextClause.bindparams() method supersedes the argument bindparams passed to text().

method sqlalchemy.sql.expression.TextClause.columns(selectable, *cols, **types)

Turn this TextClause object into a TextAsFrom object that can be embedded into another statement.

This function essentially bridges the gap between an entirely textual SELECT statement and the SQL expression language concept of a “selectable”:

from sqlalchemy.sql import column, text

stmt = text("SELECT id, name FROM some_table")
stmt = stmt.columns(column('id'), column('name')).alias('st')

stmt = select([mytable]).                    select_from(
            mytable.join(stmt, mytable.c.name == stmt.c.name)
        ).where(stmt.c.id > 5)

Above, we pass a series of column() elements to the TextClause.columns() method positionally. These column() elements now become first class elements upon the TextAsFrom.c column collection, just like any other selectable.

The column expressions we pass to TextClause.columns() may also be typed; when we do so, these TypeEngine objects become the effective return type of the column, so that SQLAlchemy’s result-set-processing systems may be used on the return values. This is often needed for types such as date or boolean types, as well as for unicode processing on some dialect configurations:

stmt = text("SELECT id, name, timestamp FROM some_table")
stmt = stmt.columns(
            column('id', Integer),
            column('name', Unicode),
            column('timestamp', DateTime)
        )

for id, name, timestamp in connection.execute(stmt):
    print(id, name, timestamp)

As a shortcut to the above syntax, keyword arguments referring to types alone may be used, if only type conversion is needed:

stmt = text("SELECT id, name, timestamp FROM some_table")
stmt = stmt.columns(
            id=Integer,
            name=Unicode,
            timestamp=DateTime
        )

for id, name, timestamp in connection.execute(stmt):
    print(id, name, timestamp)

The positional form of TextClause.columns() also provides the unique feature of positional column targeting, which is particularly useful when using the ORM with complex textual queries. If we specify the columns from our model to TextClause.columns(), the result set will match to those columns positionally, meaning the name or origin of the column in the textual SQL doesn’t matter:

stmt = text("SELECT users.id, addresses.id, users.id, "
     "users.name, addresses.email_address AS email "
     "FROM users JOIN addresses ON users.id=addresses.user_id "
     "WHERE users.id = 1").columns(
        User.id,
        Address.id,
        Address.user_id,
        User.name,
        Address.email_address
     )

query = session.query(User).from_statement(stmt).options(
    contains_eager(User.addresses))

New in version 1.1: the TextClause.columns() method now offers positional column targeting in the result set when the column expressions are passed purely positionally.

The TextClause.columns() method provides a direct route to calling FromClause.alias() as well as SelectBase.cte() against a textual SELECT statement:

stmt = stmt.columns(id=Integer, name=String).cte('st')

stmt = select([sometable]).where(sometable.c.id == stmt.c.id)

New in version 0.9.0: text() can now be converted into a fully featured “selectable” construct using the TextClause.columns() method. This method supersedes the typemap argument to text().

method sqlalchemy.sql.expression.TextClause.compare(other)

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.TextClause.get_children(**kwargs)

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs 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.TextClause.self_group(against=None)

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.Tuple(*clauses, **kw)

Represent a SQL tuple.

Members

__init__()

Class signature

class sqlalchemy.sql.expression.Tuple (sqlalchemy.sql.expression.ClauseList, sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.Tuple.__init__(*clauses, **kw)

Construct a new Tuple object.

This constructor is mirrored as a public API function; see tuple_() for a full usage and argument description.

class sqlalchemy.sql.expression.WithinGroup(element, *order_by)

Represent a WITHIN GROUP (ORDER BY) clause.

This is a special operator against so-called “ordered set aggregate” and “hypothetical set aggregate” functions, including percentile_cont(), rank(), dense_rank(), etc.

It’s supported only by certain database backends, such as PostgreSQL, Oracle and MS SQL Server.

The WithinGroup construct extracts its type from the method FunctionElement.within_group_type(). If this returns None, the function’s .type is used.

Members

__init__(), get_children(), over()

Class signature

class sqlalchemy.sql.expression.WithinGroup (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.WithinGroup.__init__(element, *order_by)

Construct a new WithinGroup object.

This constructor is mirrored as a public API function; see within_group() for a full usage and argument description.

method sqlalchemy.sql.expression.WithinGroup.get_children(**kwargs)

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs 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.WithinGroup.over(partition_by=None, order_by=None, range_=None, rows=None)

Produce an OVER clause against this WithinGroup construct.

This function has the same signature as that of FunctionElement.over().

class sqlalchemy.sql.elements.True_

Represent the true keyword, or equivalent, in a SQL statement.

True_ is accessed as a constant via the true() function.

Members

compare()

Class signature

class sqlalchemy.sql.expression.True_ (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.elements.True_.compare(other)

Compare this ColumnElement to another.

Special arguments understood:

Parameters:

• use_proxies – when True, consider two columns that share a common base column as equivalent (i.e. shares_lineage())

• equivalents – a dictionary of columns as keys mapped to sets of columns. If the given “other” column is present in this dictionary, if any of the columns in the corresponding set() pass the comparison test, the result is True. This is used to expand the comparison to other columns that may be known to be equivalent to this one via foreign key or other criterion.

class sqlalchemy.sql.expression.TypeCoerce(expression, type_)

Represent a Python-side type-coercion wrapper.

TypeCoerce supplies the type_coerce() function; see that function for usage details.

Changed in version 1.1: The type_coerce() function now produces a persistent TypeCoerce wrapper object rather than translating the given object in place.

See also

type_coerce()

Members

__init__(), get_children()

Class signature

class sqlalchemy.sql.expression.TypeCoerce (sqlalchemy.sql.expression.ColumnElement)

method sqlalchemy.sql.expression.TypeCoerce.__init__(expression, type_)

Construct a new TypeCoerce object.

This constructor is mirrored as a public API function; see type_coerce() for a full usage and argument description.

method sqlalchemy.sql.expression.TypeCoerce.get_children(**kwargs)

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs 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).

class sqlalchemy.sql.operators.custom_op(opstring, precedence=0, is_comparison=False, return_type=None, natural_self_precedent=False, eager_grouping=False)

Represent a ‘custom’ operator.

custom_op is normally instantiated when the Operators.op() or Operators.bool_op() methods are used to create a custom operator callable. The class can also be used directly when programmatically constructing expressions. E.g. to represent the “factorial” operation:

from sqlalchemy.sql import UnaryExpression
from sqlalchemy.sql import operators
from sqlalchemy import Numeric

unary = UnaryExpression(table.c.somecolumn,
        modifier=operators.custom_op("!"),
        type_=Numeric)

See also

Operators.op()

Operators.bool_op()

class sqlalchemy.sql.operators.Operators

Base of comparison and logical operators.

Implements base methods Operators.operate() and Operators.reverse_operate(), as well as Operators.__and__(), Operators.__or__(), Operators.__invert__().

Members

__and__(), __invert__(), __or__(), bool_op(), op(), operate(), reverse_operate()

Usually is used via its most common subclass ColumnOperators.

method sqlalchemy.sql.operators.Operators.__and__(other)

Implement the & operator.

When used with SQL expressions, results in an AND operation, equivalent to and_(), that is:

a & b

is equivalent to:

from sqlalchemy import and_
and_(a, b)

Care should be taken when using & regarding operator precedence; the & operator has the highest precedence. The operands should be enclosed in parenthesis if they contain further sub expressions:

(a == 2) & (b == 4)

method sqlalchemy.sql.operators.Operators.__invert__()

Implement the ~ operator.

When used with SQL expressions, results in a NOT operation, equivalent to not_(), that is:

~a

is equivalent to:

from sqlalchemy import not_
not_(a)

method sqlalchemy.sql.operators.Operators.__or__(other)

Implement the | operator.

When used with SQL expressions, results in an OR operation, equivalent to or_(), that is:

a | b

is equivalent to:

from sqlalchemy import or_
or_(a, b)

Care should be taken when using | regarding operator precedence; the | operator has the highest precedence. The operands should be enclosed in parenthesis if they contain further sub expressions:

(a == 2) | (b == 4)

method sqlalchemy.sql.operators.Operators.bool_op(opstring, precedence=0)

Return a custom boolean operator.

This method is shorthand for calling Operators.op() and passing the Operators.op.is_comparison flag with True.

New in version 1.2.0b3.

See also

Operators.op()

method sqlalchemy.sql.operators.Operators.op(opstring, precedence=0, is_comparison=False, return_type=None)

produce a generic operator function.

e.g.:

somecolumn.op("*")(5)

produces:

somecolumn * 5

This function can also be used to make bitwise operators explicit. For example:

somecolumn.op('&')(0xff)

is a bitwise AND of the value in somecolumn.

Parameters:

• operator – a string which will be output as the infix operator between this element and the expression passed to the generated function.

• precedence – precedence to apply to the operator, when parenthesizing expressions. A lower number will cause the expression to be parenthesized when applied against another operator with higher precedence. The default value of 0 is lower than all operators except for the comma (,) and AS operators. A value of 100 will be higher or equal to all operators, and -100 will be lower than or equal to all operators.

• is_comparison –

  if True, the operator will be considered as a “comparison” operator, that is which evaluates to a boolean true/false value, like ==, >, etc. This flag should be set so that ORM relationships can establish that the operator is a comparison operator when used in a custom join condition.

  New in version 0.9.2: - added the Operators.op.is_comparison flag.

• return_type –

  a TypeEngine class or object that will force the return type of an expression produced by this operator to be of that type. By default, operators that specify Operators.op.is_comparison will resolve to Boolean, and those that do not will be of the same type as the left-hand operand.

  New in version 1.2.0b3: - added the Operators.op.return_type argument.

See also

Redefining and Creating New Operators

Using custom operators in join conditions

method sqlalchemy.sql.operators.Operators.operate(op, *other, **kwargs)

Operate on an argument.

This is the lowest level of operation, raises NotImplementedError by default.

Overriding this on a subclass can allow common behavior to be applied to all operations. For example, overriding ColumnOperators to apply func.lower() to the left and right side:

class MyComparator(ColumnOperators):
    def operate(self, op, other):
        return op(func.lower(self), func.lower(other))

Parameters:

• op – Operator callable.

• *other – the ‘other’ side of the operation. Will be a single scalar for most operations.

• **kwargs – modifiers. These may be passed by special operators such as ColumnOperators.contains().

method sqlalchemy.sql.operators.Operators.reverse_operate(op, other, **kwargs)

Reverse operate on an argument.

Usage is the same as operate().

class sqlalchemy.sql.elements.quoted_name(value, quote)

Represent a SQL identifier combined with quoting preferences.

quoted_name is a Python unicode/str subclass which represents a particular identifier name along with a quote flag. This quote flag, when set to True or False, overrides automatic quoting behavior for this identifier in order to either unconditionally quote or to not quote the name. If left at its default of None, quoting behavior is applied to the identifier on a per-backend basis based on an examination of the token itself.

A quoted_name object with quote=True is also prevented from being modified in the case of a so-called “name normalize” option. Certain database backends, such as Oracle, Firebird, and DB2 “normalize” case-insensitive names as uppercase. The SQLAlchemy dialects for these backends convert from SQLAlchemy’s lower-case-means-insensitive convention to the upper-case-means-insensitive conventions of those backends. The quote=True flag here will prevent this conversion from occurring to support an identifier that’s quoted as all lower case against such a backend.

The quoted_name object is normally created automatically when specifying the name for key schema constructs such as Table, Column, and others. The class can also be passed explicitly as the name to any function that receives a name which can be quoted. Such as to use the Engine.has_table() method with an unconditionally quoted name:

from sqlalchemy import create_engine
from sqlalchemy.sql import quoted_name

engine = create_engine("oracle+cx_oracle://some_dsn")
engine.has_table(quoted_name("some_table", True))

The above logic will run the “has table” logic against the Oracle backend, passing the name exactly as "some_table" without converting to upper case.

New in version 0.9.0.

Changed in version 1.2: The quoted_name construct is now importable from sqlalchemy.sql, in addition to the previous location of sqlalchemy.sql.elements.

Members

quote

Class signature

class sqlalchemy.sql.expression.quoted_name (sqlalchemy.util.langhelpers.MemoizedSlots, builtins.str)

attribute sqlalchemy.sql.elements.quoted_name.quote

whether the string should be unconditionally quoted

class sqlalchemy.sql.expression.UnaryExpression(element, operator=None, modifier=None, type_=None, negate=None, wraps_column_expression=False)

Define a ‘unary’ expression.

A unary expression has a single column expression and an operator. The operator can be placed on the left (where it is called the ‘operator’) or right (where it is called the ‘modifier’) of the column expression.

UnaryExpression is the basis for several unary operators including those used by desc(), asc(), distinct(), nullsfirst() and nullslast().

Members

compare(), get_children(), self_group()

Class signature

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

method sqlalchemy.sql.expression.UnaryExpression.compare(other, **kw)

Compare this UnaryExpression against the given ClauseElement.

method sqlalchemy.sql.expression.UnaryExpression.get_children(**kwargs)

Return immediate child elements of this ClauseElement.

This is used for visit traversal.

**kwargs 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.UnaryExpression.self_group(against=None)

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.