MySQL¶

Support for the MySQL database.

The following table summarizes current support levels for database release versions.

DBAPI Support¶

The following dialect/DBAPI options are available. Please refer to individual DBAPI sections for connect information.

mysqlclient (maintained fork of MySQL-Python)
PyMySQL
MySQL Connector/Python
CyMySQL
OurSQL
Google Cloud SQL
PyODBC
zxjdbc for Jython

Supported Versions and Features¶

SQLAlchemy supports MySQL starting with version 4.1 through modern releases. However, no heroic measures are taken to work around major missing SQL features - if your server version does not support sub-selects, for example, they won’t work in SQLAlchemy either.

See the official MySQL documentation for detailed information about features supported in any given server release.

Connection Timeouts and Disconnects¶

MySQL features an automatic connection close behavior, for connections that have been idle for a fixed period of time, defaulting to eight hours. To circumvent having this issue, use the create_engine.pool_recycle option which ensures that a connection will be discarded and replaced with a new one if it has been present in the pool for a fixed number of seconds:

engine = create_engine('mysql+mysqldb://...', pool_recycle=3600)

For more comprehensive disconnect detection of pooled connections, including accommodation of server restarts and network issues, a pre-ping approach may be employed. See Dealing with Disconnects for current approaches.

See also

Dealing with Disconnects - Background on several techniques for dealing with timed out connections as well as database restarts.

CREATE TABLE arguments including Storage Engines¶

MySQL’s CREATE TABLE syntax includes a wide array of special options, including ENGINE, CHARSET, MAX_ROWS, ROW_FORMAT, INSERT_METHOD, and many more. To accommodate the rendering of these arguments, specify the form mysql_argument_name="value". For example, to specify a table with ENGINE of InnoDB, CHARSET of utf8mb4, and KEY_BLOCK_SIZE of 1024:

Table('mytable', metadata,
      Column('data', String(32)),
      mysql_engine='InnoDB',
      mysql_charset='utf8mb4',
      mysql_key_block_size="1024"
     )

The MySQL dialect will normally transfer any keyword specified as mysql_keyword_name to be rendered as KEYWORD_NAME in the CREATE TABLE statement. A handful of these names will render with a space instead of an underscore; to support this, the MySQL dialect has awareness of these particular names, which include DATA DIRECTORY (e.g. mysql_data_directory), CHARACTER SET (e.g. mysql_character_set) and INDEX DIRECTORY (e.g. mysql_index_directory).

The most common argument is mysql_engine, which refers to the storage engine for the table. Historically, MySQL server installations would default to MyISAM for this value, although newer versions may be defaulting to InnoDB. The InnoDB engine is typically preferred for its support of transactions and foreign keys.

A Table that is created in a MySQL database with a storage engine of MyISAM will be essentially non-transactional, meaning any INSERT/UPDATE/DELETE statement referring to this table will be invoked as autocommit. It also will have no support for foreign key constraints; while the CREATE TABLE statement accepts foreign key options, when using the MyISAM storage engine these arguments are discarded. Reflecting such a table will also produce no foreign key constraint information.

For fully atomic transactions as well as support for foreign key constraints, all participating CREATE TABLE statements must specify a transactional engine, which in the vast majority of cases is InnoDB.

See also

The InnoDB Storage Engine - on the MySQL website.

Case Sensitivity and Table Reflection¶

MySQL has inconsistent support for case-sensitive identifier names, basing support on specific details of the underlying operating system. However, it has been observed that no matter what case sensitivity behavior is present, the names of tables in foreign key declarations are always received from the database as all-lower case, making it impossible to accurately reflect a schema where inter-related tables use mixed-case identifier names.

Therefore it is strongly advised that table names be declared as all lower case both within SQLAlchemy as well as on the MySQL database itself, especially if database reflection features are to be used.

Transaction Isolation Level¶

All MySQL dialects support setting of transaction isolation level both via a dialect-specific parameter create_engine.isolation_level accepted by create_engine(), as well as the Connection.execution_options.isolation_level argument as passed to Connection.execution_options(). This feature works by issuing the command SET SESSION TRANSACTION ISOLATION LEVEL <level> for each new connection. For the special AUTOCOMMIT isolation level, DBAPI-specific techniques are used.

To set isolation level using create_engine():

engine = create_engine(
                "mysql://scott:tiger@localhost/test",
                isolation_level="READ UNCOMMITTED"
            )

To set using per-connection execution options:

connection = engine.connect()
connection = connection.execution_options(
    isolation_level="READ COMMITTED"
)

Valid values for isolation_level include:

READ COMMITTED
READ UNCOMMITTED
REPEATABLE READ
SERIALIZABLE
AUTOCOMMIT

The special AUTOCOMMIT value makes use of the various “autocommit” attributes provided by specific DBAPIs, and is currently supported by MySQLdb, MySQL-Client, MySQL-Connector Python, and PyMySQL. Using it, the MySQL connection will return true for the value of SELECT @@autocommit;.

AUTO_INCREMENT Behavior¶

When creating tables, SQLAlchemy will automatically set AUTO_INCREMENT on the first Integer primary key column which is not marked as a foreign key:

>>> t = Table('mytable', metadata,
...   Column('mytable_id', Integer, primary_key=True)
... )
>>> t.create()
CREATE TABLE mytable (
        id INTEGER NOT NULL AUTO_INCREMENT,
        PRIMARY KEY (id)
)

You can disable this behavior by passing False to the Column.autoincrement argument of Column. This flag can also be used to enable auto-increment on a secondary column in a multi-column key for some storage engines:

Table('mytable', metadata,
      Column('gid', Integer, primary_key=True, autoincrement=False),
      Column('id', Integer, primary_key=True)
     )

Server Side Cursors¶

Server-side cursor support is available for the MySQLdb and PyMySQL dialects. From a MySQL point of view this means that the MySQLdb.cursors.SSCursor or pymysql.cursors.SSCursor class is used when building up the cursor which will receive results. The most typical way of invoking this feature is via the Connection.execution_options.stream_results connection execution option. Server side cursors can also be enabled for all SELECT statements unconditionally by passing server_side_cursors=True to create_engine().

New in version 1.1.4: - added server-side cursor support.

Unicode¶

Charset Selection¶

Most MySQL DBAPIs offer the option to set the client character set for a connection. This is typically delivered using the charset parameter in the URL, such as:

e = create_engine(
    "mysql+pymysql://scott:tiger@localhost/test?charset=utf8mb4")

This charset is the client character set for the connection. Some MySQL DBAPIs will default this to a value such as latin1, and some will make use of the default-character-set setting in the my.cnf file as well. Documentation for the DBAPI in use should be consulted for specific behavior.

The encoding used for Unicode has traditionally been 'utf8'. However, for MySQL versions 5.5.3 on forward, a new MySQL-specific encoding 'utf8mb4' has been introduced, and as of MySQL 8.0 a warning is emitted by the server if plain utf8 is specified within any server-side directives, replaced with utf8mb3. The rationale for this new encoding is due to the fact that MySQL’s legacy utf-8 encoding only supports codepoints up to three bytes instead of four. Therefore, when communicating with a MySQL database that includes codepoints more than three bytes in size, this new charset is preferred, if supported by both the database as well as the client DBAPI, as in:

e = create_engine(
    "mysql+pymysql://scott:tiger@localhost/test?charset=utf8mb4")

All modern DBAPIs should support the utf8mb4 charset.

In order to use utf8mb4 encoding for a schema that was created with legacy utf8, changes to the MySQL schema and/or server configuration may be required.

See also

The utf8mb4 Character Set - in the MySQL documentation

Dealing with Binary Data Warnings and Unicode¶

MySQL versions 5.6, 5.7 and later (not MariaDB at the time of this writing) now emit a warning when attempting to pass binary data to the database, while a character set encoding is also in place, when the binary data itself is not valid for that encoding:

default.py:509: Warning: (1300, "Invalid utf8mb4 character string:
'F9876A'")
  cursor.execute(statement, parameters)

This warning is due to the fact that the MySQL client library is attempting to interpret the binary string as a unicode object even if a datatype such as LargeBinary is in use. To resolve this, the SQL statement requires a binary “character set introducer” be present before any non-NULL value that renders like this:

INSERT INTO table (data) VALUES (_binary %s)

These character set introducers are provided by the DBAPI driver, assuming the use of mysqlclient or PyMySQL (both of which are recommended). Add the query string parameter binary_prefix=true to the URL to repair this warning:

# mysqlclient
engine = create_engine(
    "mysql+mysqldb://scott:tiger@localhost/test?charset=utf8mb4&binary_prefix=true")

# PyMySQL
engine = create_engine(
    "mysql+pymysql://scott:tiger@localhost/test?charset=utf8mb4&binary_prefix=true")

The binary_prefix flag may or may not be supported by other MySQL drivers.

SQLAlchemy itself cannot render this _binary prefix reliably, as it does not work with the NULL value, which is valid to be sent as a bound parameter. As the MySQL driver renders parameters directly into the SQL string, it’s the most efficient place for this additional keyword to be passed.

See also

Character set introducers - on the MySQL website

ANSI Quoting Style¶

MySQL features two varieties of identifier “quoting style”, one using backticks and the other using quotes, e.g. `some_identifier` vs. "some_identifier". All MySQL dialects detect which version is in use by checking the value of sql_mode when a connection is first established with a particular Engine. This quoting style comes into play when rendering table and column names as well as when reflecting existing database structures. The detection is entirely automatic and no special configuration is needed to use either quoting style.

MySQL SQL Extensions¶

Many of the MySQL SQL extensions are handled through SQLAlchemy’s generic function and operator support:

table.select(table.c.password==func.md5('plaintext'))
table.select(table.c.username.op('regexp')('^[a-d]'))

And of course any valid MySQL statement can be executed as a string as well.

Some limited direct support for MySQL extensions to SQL is currently available.

INSERT..ON DUPLICATE KEY UPDATE: See INSERT…ON DUPLICATE KEY UPDATE (Upsert)

SELECT pragma, use Select.prefix_with() and Query.prefix_with():

select(...).prefix_with(['HIGH_PRIORITY', 'SQL_SMALL_RESULT'])

UPDATE with LIMIT:
```
update(..., mysql_limit=10)
```

optimizer hints, use Select.prefix_with() and Query.prefix_with():

select(...).prefix_with("/*+ NO_RANGE_OPTIMIZATION(t4 PRIMARY) */")

index hints, use Select.with_hint() and Query.with_hint():
```
select(...).with_hint(some_table, "USE INDEX xyz")
```

INSERT…ON DUPLICATE KEY UPDATE (Upsert)¶

MySQL allows “upserts” (update or insert) of rows into a table via the ON DUPLICATE KEY UPDATE clause of the INSERT statement. A candidate row will only be inserted if that row does not match an existing primary or unique key in the table; otherwise, an UPDATE will be performed. The statement allows for separate specification of the values to INSERT versus the values for UPDATE.

SQLAlchemy provides ON DUPLICATE KEY UPDATE support via the MySQL-specific insert() function, which provides the generative method Insert.on_duplicate_key_update():

from sqlalchemy.dialects.mysql import insert

insert_stmt = insert(my_table).values(
    id='some_existing_id',
    data='inserted value')

on_duplicate_key_stmt = insert_stmt.on_duplicate_key_update(
    data=insert_stmt.inserted.data,
    status='U'
)

conn.execute(on_duplicate_key_stmt)

Unlike PostgreSQL’s “ON CONFLICT” phrase, the “ON DUPLICATE KEY UPDATE” phrase will always match on any primary key or unique key, and will always perform an UPDATE if there’s a match; there are no options for it to raise an error or to skip performing an UPDATE.

ON DUPLICATE KEY UPDATE is used to perform an update of the already existing row, using any combination of new values as well as values from the proposed insertion. These values are normally specified using keyword arguments passed to the Insert.on_duplicate_key_update() given column key values (usually the name of the column, unless it specifies Column.key ) as keys and literal or SQL expressions as values:

on_duplicate_key_stmt = insert_stmt.on_duplicate_key_update(
    data="some data",
    updated_at=func.current_timestamp(),
)

In a manner similar to that of UpdateBase.values(), other parameter forms are accepted, including a single dictionary:

on_duplicate_key_stmt = insert_stmt.on_duplicate_key_update(
    {"data": "some data", "updated_at": func.current_timestamp()},
)

as well as a list of 2-tuples, which will automatically provide a parameter-ordered UPDATE statement in a manner similar to that described at Parameter-Ordered Updates. Unlike the Update object, no special flag is needed to specify the intent since the argument form is this context is unambiguous:

on_duplicate_key_stmt = insert_stmt.on_duplicate_key_update(
    [
        ("data", "some data"),
        ("updated_at", func.current_timestamp()),
    ],
)

Changed in version 1.3: support for parameter-ordered UPDATE clause within MySQL ON DUPLICATE KEY UPDATE

Warning

The Insert.on_duplicate_key_update() method does not take into account Python-side default UPDATE values or generation functions, e.g. e.g. those specified using Column.onupdate. These values will not be exercised for an ON DUPLICATE KEY style of UPDATE, unless they are manually specified explicitly in the parameters.

In order to refer to the proposed insertion row, the special alias Insert.inserted is available as an attribute on the Insert object; this object is a ColumnCollection which contains all columns of the target table:

from sqlalchemy.dialects.mysql import insert

stmt = insert(my_table).values(
    id='some_id',
    data='inserted value',
    author='jlh')
do_update_stmt = stmt.on_duplicate_key_update(
    data="updated value",
    author=stmt.inserted.author
)
conn.execute(do_update_stmt)

When rendered, the “inserted” namespace will produce the expression VALUES(<columnname>).

New in version 1.2: Added support for MySQL ON DUPLICATE KEY UPDATE clause

rowcount Support¶

SQLAlchemy standardizes the DBAPI cursor.rowcount attribute to be the usual definition of “number of rows matched by an UPDATE or DELETE” statement. This is in contradiction to the default setting on most MySQL DBAPI drivers, which is “number of rows actually modified/deleted”. For this reason, the SQLAlchemy MySQL dialects always add the constants.CLIENT.FOUND_ROWS flag, or whatever is equivalent for the target dialect, upon connection. This setting is currently hardcoded.

See also

ResultProxy.rowcount

CAST Support¶

MySQL documents the CAST operator as available in version 4.0.2. When using the SQLAlchemy cast() function, SQLAlchemy will not render the CAST token on MySQL before this version, based on server version detection, instead rendering the internal expression directly.

CAST may still not be desirable on an early MySQL version post-4.0.2, as it didn’t add all datatype support until 4.1.1. If your application falls into this narrow area, the behavior of CAST can be controlled using the Custom SQL Constructs and Compilation Extension system, as per the recipe below:

from sqlalchemy.sql.expression import Cast
from sqlalchemy.ext.compiler import compiles

@compiles(Cast, 'mysql')
def _check_mysql_version(element, compiler, **kw):
    if compiler.dialect.server_version_info < (4, 1, 0):
        return compiler.process(element.clause, **kw)
    else:
        return compiler.visit_cast(element, **kw)

The above function, which only needs to be declared once within an application, overrides the compilation of the cast() construct to check for version 4.1.0 before fully rendering CAST; else the internal element of the construct is rendered directly.

MySQL Specific Index Options¶

MySQL-specific extensions to the Index construct are available.

Index Length¶

MySQL provides an option to create index entries with a certain length, where “length” refers to the number of characters or bytes in each value which will become part of the index. SQLAlchemy provides this feature via the mysql_length parameter:

Index('my_index', my_table.c.data, mysql_length=10)

Index('a_b_idx', my_table.c.a, my_table.c.b, mysql_length={'a': 4,
                                                           'b': 9})

Prefix lengths are given in characters for nonbinary string types and in bytes for binary string types. The value passed to the keyword argument must be either an integer (and, thus, specify the same prefix length value for all columns of the index) or a dict in which keys are column names and values are prefix length values for corresponding columns. MySQL only allows a length for a column of an index if it is for a CHAR, VARCHAR, TEXT, BINARY, VARBINARY and BLOB.

Index Prefixes¶

MySQL storage engines permit you to specify an index prefix when creating an index. SQLAlchemy provides this feature via the mysql_prefix parameter on Index:

Index('my_index', my_table.c.data, mysql_prefix='FULLTEXT')

The value passed to the keyword argument will be simply passed through to the underlying CREATE INDEX, so it must be a valid index prefix for your MySQL storage engine.

New in version 1.1.5.

See also

CREATE INDEX - MySQL documentation

Index Types¶

Some MySQL storage engines permit you to specify an index type when creating an index or primary key constraint. SQLAlchemy provides this feature via the mysql_using parameter on Index:

Index('my_index', my_table.c.data, mysql_using='hash')

As well as the mysql_using parameter on PrimaryKeyConstraint:

PrimaryKeyConstraint("data", mysql_using='hash')

The value passed to the keyword argument will be simply passed through to the underlying CREATE INDEX or PRIMARY KEY clause, so it must be a valid index type for your MySQL storage engine.

More information can be found at:

http://dev.mysql.com/doc/refman/5.0/en/create-index.html

http://dev.mysql.com/doc/refman/5.0/en/create-table.html

Index Parsers¶

CREATE FULLTEXT INDEX in MySQL also supports a “WITH PARSER” option. This is available using the keyword argument mysql_with_parser:

Index(
    'my_index', my_table.c.data,
    mysql_prefix='FULLTEXT', mysql_with_parser="ngram")

New in version 1.3.

MySQL Foreign Keys¶

MySQL’s behavior regarding foreign keys has some important caveats.

Foreign Key Arguments to Avoid¶

MySQL does not support the foreign key arguments “DEFERRABLE”, “INITIALLY”, or “MATCH”. Using the deferrable or initially keyword argument with ForeignKeyConstraint or ForeignKey will have the effect of these keywords being rendered in a DDL expression, which will then raise an error on MySQL. In order to use these keywords on a foreign key while having them ignored on a MySQL backend, use a custom compile rule:

from sqlalchemy.ext.compiler import compiles
from sqlalchemy.schema import ForeignKeyConstraint

@compiles(ForeignKeyConstraint, "mysql")
def process(element, compiler, **kw):
    element.deferrable = element.initially = None
    return compiler.visit_foreign_key_constraint(element, **kw)

Changed in version 0.9.0: - the MySQL backend no longer silently ignores the deferrable or initially keyword arguments of ForeignKeyConstraint and ForeignKey.

The “MATCH” keyword is in fact more insidious, and is explicitly disallowed by SQLAlchemy in conjunction with the MySQL backend. This argument is silently ignored by MySQL, but in addition has the effect of ON UPDATE and ON DELETE options also being ignored by the backend. Therefore MATCH should never be used with the MySQL backend; as is the case with DEFERRABLE and INITIALLY, custom compilation rules can be used to correct a MySQL ForeignKeyConstraint at DDL definition time.

New in version 0.9.0: - the MySQL backend will raise a CompileError when the match keyword is used with ForeignKeyConstraint or ForeignKey.

Reflection of Foreign Key Constraints¶

Not all MySQL storage engines support foreign keys. When using the very common MyISAM MySQL storage engine, the information loaded by table reflection will not include foreign keys. For these tables, you may supply a ForeignKeyConstraint at reflection time:

Table('mytable', metadata,
      ForeignKeyConstraint(['other_id'], ['othertable.other_id']),
      autoload=True
     )

MySQL Unique Constraints and Reflection¶

SQLAlchemy supports both the Index construct with the flag unique=True, indicating a UNIQUE index, as well as the UniqueConstraint construct, representing a UNIQUE constraint. Both objects/syntaxes are supported by MySQL when emitting DDL to create these constraints. However, MySQL does not have a unique constraint construct that is separate from a unique index; that is, the “UNIQUE” constraint on MySQL is equivalent to creating a “UNIQUE INDEX”.

When reflecting these constructs, the Inspector.get_indexes() and the Inspector.get_unique_constraints() methods will both return an entry for a UNIQUE index in MySQL. However, when performing full table reflection using Table(..., autoload=True), the UniqueConstraint construct is not part of the fully reflected Table construct under any circumstances; this construct is always represented by a Index with the unique=True setting present in the Table.indexes collection.

TIMESTAMP / DATETIME issues¶

Rendering ON UPDATE CURRENT TIMESTAMP for MySQL’s explicit_defaults_for_timestamp¶

MySQL has historically expanded the DDL for the TIMESTAMP datatype into the phrase “TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP”, which includes non-standard SQL that automatically updates the column with the current timestamp when an UPDATE occurs, eliminating the usual need to use a trigger in such a case where server-side update changes are desired.

MySQL 5.6 introduced a new flag explicit_defaults_for_timestamp which disables the above behavior, and in MySQL 8 this flag defaults to true, meaning in order to get a MySQL “on update timestamp” without changing this flag, the above DDL must be rendered explicitly. Additionally, the same DDL is valid for use of the DATETIME datatype as well.

SQLAlchemy’s MySQL dialect does not yet have an option to generate MySQL’s “ON UPDATE CURRENT_TIMESTAMP” clause, noting that this is not a general purpose “ON UPDATE” as there is no such syntax in standard SQL. SQLAlchemy’s Column.server_onupdate parameter is currently not related to this special MySQL behavior.

To generate this DDL, make use of the Column.server_default parameter and pass a textual clause that also includes the ON UPDATE clause:

from sqlalchemy import Table, MetaData, Column, Integer, String, TIMESTAMP
from sqlalchemy import text

metadata = MetaData()

mytable = Table(
    "mytable",
    metadata,
    Column('id', Integer, primary_key=True),
    Column('data', String(50)),
    Column(
        'last_updated',
        TIMESTAMP,
        server_default=text("CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP")
    )
)

The same instructions apply to use of the DateTime and DATETIME datatypes:

from sqlalchemy import DateTime

mytable = Table(
    "mytable",
    metadata,
    Column('id', Integer, primary_key=True),
    Column('data', String(50)),
    Column(
        'last_updated',
        DateTime,
        server_default=text("CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP")
    )
)

Even though the Column.server_onupdate feature does not generate this DDL, it still may be desirable to signal to the ORM that this updated value should be fetched. This syntax looks like the following:

from sqlalchemy.schema import FetchedValue

class MyClass(Base):
    __tablename__ = 'mytable'

    id = Column(Integer, primary_key=True)
    data = Column(String(50))
    last_updated = Column(
        TIMESTAMP,
        server_default=text("CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP"),
        server_onupdate=FetchedValue()
    )

TIMESTAMP Columns and NULL¶

MySQL historically enforces that a column which specifies the TIMESTAMP datatype implicitly includes a default value of CURRENT_TIMESTAMP, even though this is not stated, and additionally sets the column as NOT NULL, the opposite behavior vs. that of all other datatypes:

mysql> CREATE TABLE ts_test (
    -> a INTEGER,
    -> b INTEGER NOT NULL,
    -> c TIMESTAMP,
    -> d TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    -> e TIMESTAMP NULL);
Query OK, 0 rows affected (0.03 sec)

mysql> SHOW CREATE TABLE ts_test;
+---------+-----------------------------------------------------
| Table   | Create Table
+---------+-----------------------------------------------------
| ts_test | CREATE TABLE `ts_test` (
  `a` int(11) DEFAULT NULL,
  `b` int(11) NOT NULL,
  `c` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  `d` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `e` timestamp NULL DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1

Above, we see that an INTEGER column defaults to NULL, unless it is specified with NOT NULL. But when the column is of type TIMESTAMP, an implicit default of CURRENT_TIMESTAMP is generated which also coerces the column to be a NOT NULL, even though we did not specify it as such.

This behavior of MySQL can be changed on the MySQL side using the explicit_defaults_for_timestamp configuration flag introduced in MySQL 5.6. With this server setting enabled, TIMESTAMP columns behave like any other datatype on the MySQL side with regards to defaults and nullability.

However, to accommodate the vast majority of MySQL databases that do not specify this new flag, SQLAlchemy emits the “NULL” specifier explicitly with any TIMESTAMP column that does not specify nullable=False. In order to accommodate newer databases that specify explicit_defaults_for_timestamp, SQLAlchemy also emits NOT NULL for TIMESTAMP columns that do specify nullable=False. The following example illustrates:

from sqlalchemy import MetaData, Integer, Table, Column, text
from sqlalchemy.dialects.mysql import TIMESTAMP

m = MetaData()
t = Table('ts_test', m,
        Column('a', Integer),
        Column('b', Integer, nullable=False),
        Column('c', TIMESTAMP),
        Column('d', TIMESTAMP, nullable=False)
    )


from sqlalchemy import create_engine
e = create_engine("mysql://scott:tiger@localhost/test", echo=True)
m.create_all(e)

output:

CREATE TABLE ts_test (
    a INTEGER,
    b INTEGER NOT NULL,
    c TIMESTAMP NULL,
    d TIMESTAMP NOT NULL
)

Changed in version 1.0.0: - SQLAlchemy now renders NULL or NOT NULL in all cases for TIMESTAMP columns, to accommodate explicit_defaults_for_timestamp. Prior to this version, it will not render “NOT NULL” for a TIMESTAMP column that is nullable=False.

MySQL Data Types¶

As with all SQLAlchemy dialects, all UPPERCASE types that are known to be valid with MySQL are importable from the top level dialect:

from sqlalchemy.dialects.mysql import \
        BIGINT, BINARY, BIT, BLOB, BOOLEAN, CHAR, DATE, \
        DATETIME, DECIMAL, DECIMAL, DOUBLE, ENUM, FLOAT, INTEGER, \
        LONGBLOB, LONGTEXT, MEDIUMBLOB, MEDIUMINT, MEDIUMTEXT, NCHAR, \
        NUMERIC, NVARCHAR, REAL, SET, SMALLINT, TEXT, TIME, TIMESTAMP, \
        TINYBLOB, TINYINT, TINYTEXT, VARBINARY, VARCHAR, YEAR

Types which are specific to MySQL, or have MySQL-specific construction arguments, are as follows:

Object Name	Description
BIGINT	MySQL BIGINTEGER type.
BINARY	The SQL BINARY type.
BIT	MySQL BIT type.
BLOB	The SQL BLOB type.
BOOLEAN	The SQL BOOLEAN type.
CHAR	MySQL CHAR type, for fixed-length character data.
DATE	The SQL DATE type.
DATETIME	MySQL DATETIME type.
DECIMAL	MySQL DECIMAL type.
DOUBLE	MySQL DOUBLE type.
ENUM	MySQL ENUM type.
FLOAT	MySQL FLOAT type.
INTEGER	MySQL INTEGER type.
JSON	MySQL JSON type.
LONGBLOB	MySQL LONGBLOB type, for binary data up to 2^32 bytes.
LONGTEXT	MySQL LONGTEXT type, for text up to 2^32 characters.
MEDIUMBLOB	MySQL MEDIUMBLOB type, for binary data up to 2^24 bytes.
MEDIUMINT	MySQL MEDIUMINTEGER type.
MEDIUMTEXT	MySQL MEDIUMTEXT type, for text up to 2^24 characters.
NCHAR	MySQL NCHAR type.
NUMERIC	MySQL NUMERIC type.
NVARCHAR	MySQL NVARCHAR type.
REAL	MySQL REAL type.
SET	MySQL SET type.
SMALLINT	MySQL SMALLINTEGER type.
TEXT	MySQL TEXT type, for text up to 2^16 characters.
TIME	MySQL TIME type.
TIMESTAMP	MySQL TIMESTAMP type.
TINYBLOB	MySQL TINYBLOB type, for binary data up to 2^8 bytes.
TINYINT	MySQL TINYINT type.
TINYTEXT	MySQL TINYTEXT type, for text up to 2^8 characters.
VARBINARY	The SQL VARBINARY type.
VARCHAR	MySQL VARCHAR type, for variable-length character data.
YEAR	MySQL YEAR type, for single byte storage of years 1901-2155.

class sqlalchemy.dialects.mysql.BIGINT(display_width=None, **kw)¶

MySQL BIGINTEGER type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.BIGINT (sqlalchemy.dialects.mysql.types._IntegerType, sqlalchemy.types.BIGINT)

method sqlalchemy.dialects.mysql.BIGINT.__init__(display_width=None, **kw)¶

Construct a BIGINTEGER.

Parameters:

display_width – Optional, maximum display width for this number.
unsigned – a boolean, optional.
zerofill – Optional. If true, values will be stored as strings left-padded with zeros. Note that this does not effect the values returned by the underlying database API, which continue to be numeric.

class sqlalchemy.dialects.mysql.BINARY(length=None)¶: The SQL BINARY type.

Class signature

class sqlalchemy.dialects.mysql.BINARY (sqlalchemy.types._Binary)

class sqlalchemy.dialects.mysql.BIT(length=None)¶

MySQL BIT type.

This type is for MySQL 5.0.3 or greater for MyISAM, and 5.0.5 or greater for MyISAM, MEMORY, InnoDB and BDB. For older versions, use a MSTinyInteger() type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.BIT (sqlalchemy.types.TypeEngine)

method sqlalchemy.dialects.mysql.BIT.__init__(length=None)¶

Construct a BIT.

Parameters:: length – Optional, number of bits.

class sqlalchemy.dialects.mysql.BLOB(length=None)¶

The SQL BLOB type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.BLOB (sqlalchemy.types.LargeBinary)

method sqlalchemy.dialects.mysql.BLOB.__init__(length=None)¶

inherited from the sqlalchemy.types.LargeBinary.__init__ method of LargeBinary

Construct a LargeBinary type.

Parameters:: length – optional, a length for the column for use in DDL statements, for those binary types that accept a length, such as the MySQL BLOB type.

class sqlalchemy.dialects.mysql.BOOLEAN(create_constraint=True, name=None, _create_events=True)¶

The SQL BOOLEAN type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.BOOLEAN (sqlalchemy.types.Boolean)

method sqlalchemy.dialects.mysql.BOOLEAN.__init__(create_constraint=True, name=None, _create_events=True)¶

inherited from the sqlalchemy.types.Boolean.__init__ method of Boolean

Construct a Boolean.

Parameters:

create_constraint – defaults to True. If the boolean is generated as an int/smallint, also create a CHECK constraint on the table that ensures 1 or 0 as a value.
name – if a CHECK constraint is generated, specify the name of the constraint.

class sqlalchemy.dialects.mysql.CHAR(length=None, **kwargs)¶

MySQL CHAR type, for fixed-length character data.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.CHAR (sqlalchemy.dialects.mysql.types._StringType, sqlalchemy.types.CHAR)

method sqlalchemy.dialects.mysql.CHAR.__init__(length=None, **kwargs)¶

Construct a CHAR.

Parameters:

length – Maximum data length, in characters.
binary – Optional, use the default binary collation for the national character set. This does not affect the type of data stored, use a BINARY type for binary data.
collation – Optional, request a particular collation. Must be compatible with the national character set.

class sqlalchemy.dialects.mysql.DATE¶: The SQL DATE type.

Class signature

class sqlalchemy.dialects.mysql.DATE (sqlalchemy.types.Date)

class sqlalchemy.dialects.mysql.DATETIME(timezone=False, fsp=None)¶

MySQL DATETIME type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.DATETIME (sqlalchemy.types.DATETIME)

method sqlalchemy.dialects.mysql.DATETIME.__init__(timezone=False, fsp=None)¶

Construct a MySQL DATETIME type.

Parameters:

timezone – not used by the MySQL dialect.
fsp –
fractional seconds precision value. MySQL 5.6.4 supports storage of fractional seconds; this parameter will be used when emitting DDL for the DATETIME type.

Note

DBAPI driver support for fractional seconds may be limited; current support includes MySQL Connector/Python.

class sqlalchemy.dialects.mysql.DECIMAL(precision=None, scale=None, asdecimal=True, **kw)¶

MySQL DECIMAL type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.DECIMAL (sqlalchemy.dialects.mysql.types._NumericType, sqlalchemy.types.DECIMAL)

method sqlalchemy.dialects.mysql.DECIMAL.__init__(precision=None, scale=None, asdecimal=True, **kw)¶

Construct a DECIMAL.

Parameters:

precision – Total digits in this number. If scale and precision are both None, values are stored to limits allowed by the server.
scale – The number of digits after the decimal point.
unsigned – a boolean, optional.
zerofill – Optional. If true, values will be stored as strings left-padded with zeros. Note that this does not effect the values returned by the underlying database API, which continue to be numeric.

class sqlalchemy.dialects.mysql.DOUBLE(precision=None, scale=None, asdecimal=True, **kw)¶

MySQL DOUBLE type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.DOUBLE (sqlalchemy.dialects.mysql.types._FloatType)

method sqlalchemy.dialects.mysql.DOUBLE.__init__(precision=None, scale=None, asdecimal=True, **kw)¶

Construct a DOUBLE.

Note

The DOUBLE type by default converts from float to Decimal, using a truncation that defaults to 10 digits. Specify either scale=n or decimal_return_scale=n in order to change this scale, or asdecimal=False to return values directly as Python floating points.

Parameters:

precision – Total digits in this number. If scale and precision are both None, values are stored to limits allowed by the server.
scale – The number of digits after the decimal point.
unsigned – a boolean, optional.
zerofill – Optional. If true, values will be stored as strings left-padded with zeros. Note that this does not effect the values returned by the underlying database API, which continue to be numeric.

class sqlalchemy.dialects.mysql.ENUM(*enums, **kw)¶

MySQL ENUM type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.ENUM (sqlalchemy.types.NativeForEmulated, sqlalchemy.types.Enum, sqlalchemy.dialects.mysql.enumerated._EnumeratedValues)

method sqlalchemy.dialects.mysql.ENUM.__init__(*enums, **kw)¶

Construct an ENUM.

E.g.:

Column('myenum', ENUM("foo", "bar", "baz"))

Parameters:

enums –
The range of valid values for this ENUM. Values will be quoted when generating the schema according to the quoting flag (see below). This object may also be a PEP-435-compliant enumerated type.
strict –
This flag has no effect.

Changed in version The: MySQL ENUM type as well as the base Enum type now validates all Python data values.
charset – Optional, a column-level character set for this string value. Takes precedence to ‘ascii’ or ‘unicode’ short-hand.
collation – Optional, a column-level collation for this string value. Takes precedence to ‘binary’ short-hand.
ascii – Defaults to False: short-hand for the latin1 character set, generates ASCII in schema.
unicode – Defaults to False: short-hand for the ucs2 character set, generates UNICODE in schema.
binary – Defaults to False: short-hand, pick the binary collation type that matches the column’s character set. Generates BINARY in schema. This does not affect the type of data stored, only the collation of character data.
quoting –
Defaults to ‘auto’: automatically determine enum value quoting. If all enum values are surrounded by the same quoting character, then use ‘quoted’ mode. Otherwise, use ‘unquoted’ mode.

’quoted’: values in enums are already quoted, they will be used directly when generating the schema - this usage is deprecated.

’unquoted’: values in enums are not quoted, they will be escaped and surrounded by single quotes when generating the schema.

Previous versions of this type always required manually quoted values to be supplied; future versions will always quote the string literals for you. This is a transitional option.

class sqlalchemy.dialects.mysql.FLOAT(precision=None, scale=None, asdecimal=False, **kw)¶

MySQL FLOAT type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.FLOAT (sqlalchemy.dialects.mysql.types._FloatType, sqlalchemy.types.FLOAT)

method sqlalchemy.dialects.mysql.FLOAT.__init__(precision=None, scale=None, asdecimal=False, **kw)¶

Construct a FLOAT.

Parameters:

precision – Total digits in this number. If scale and precision are both None, values are stored to limits allowed by the server.
scale – The number of digits after the decimal point.
unsigned – a boolean, optional.
zerofill – Optional. If true, values will be stored as strings left-padded with zeros. Note that this does not effect the values returned by the underlying database API, which continue to be numeric.

class sqlalchemy.dialects.mysql.INTEGER(display_width=None, **kw)¶

MySQL INTEGER type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.INTEGER (sqlalchemy.dialects.mysql.types._IntegerType, sqlalchemy.types.INTEGER)

method sqlalchemy.dialects.mysql.INTEGER.__init__(display_width=None, **kw)¶

Construct an INTEGER.

Parameters:

display_width – Optional, maximum display width for this number.
unsigned – a boolean, optional.
zerofill – Optional. If true, values will be stored as strings left-padded with zeros. Note that this does not effect the values returned by the underlying database API, which continue to be numeric.

class sqlalchemy.dialects.mysql.JSON(none_as_null=False)¶

MySQL JSON type.

MySQL supports JSON as of version 5.7. MariaDB supports JSON (as an alias for LONGTEXT) as of version 10.2.

The JSON type supports persistence of JSON values as well as the core index operations provided by JSON datatype, by adapting the operations to render the JSON_EXTRACT function at the database level.

New in version 1.1.

Class signature

class sqlalchemy.dialects.mysql.JSON (sqlalchemy.types.JSON)

class sqlalchemy.dialects.mysql.LONGBLOB(length=None)¶: MySQL LONGBLOB type, for binary data up to 2^32 bytes.

Class signature

class sqlalchemy.dialects.mysql.LONGBLOB (sqlalchemy.types._Binary)

class sqlalchemy.dialects.mysql.LONGTEXT(**kwargs)¶

MySQL LONGTEXT type, for text up to 2^32 characters.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.LONGTEXT (sqlalchemy.dialects.mysql.types._StringType)

method sqlalchemy.dialects.mysql.LONGTEXT.__init__(**kwargs)¶

Construct a LONGTEXT.

Parameters:

charset – Optional, a column-level character set for this string value. Takes precedence to ‘ascii’ or ‘unicode’ short-hand.
collation – Optional, a column-level collation for this string value. Takes precedence to ‘binary’ short-hand.
ascii – Defaults to False: short-hand for the latin1 character set, generates ASCII in schema.
unicode – Defaults to False: short-hand for the ucs2 character set, generates UNICODE in schema.
national – Optional. If true, use the server’s configured national character set.
binary – Defaults to False: short-hand, pick the binary collation type that matches the column’s character set. Generates BINARY in schema. This does not affect the type of data stored, only the collation of character data.

class sqlalchemy.dialects.mysql.MEDIUMBLOB(length=None)¶: MySQL MEDIUMBLOB type, for binary data up to 2^24 bytes.

Class signature

class sqlalchemy.dialects.mysql.MEDIUMBLOB (sqlalchemy.types._Binary)

class sqlalchemy.dialects.mysql.MEDIUMINT(display_width=None, **kw)¶

MySQL MEDIUMINTEGER type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.MEDIUMINT (sqlalchemy.dialects.mysql.types._IntegerType)

method sqlalchemy.dialects.mysql.MEDIUMINT.__init__(display_width=None, **kw)¶

Construct a MEDIUMINTEGER

Parameters:

display_width – Optional, maximum display width for this number.
unsigned – a boolean, optional.
zerofill – Optional. If true, values will be stored as strings left-padded with zeros. Note that this does not effect the values returned by the underlying database API, which continue to be numeric.

class sqlalchemy.dialects.mysql.MEDIUMTEXT(**kwargs)¶

MySQL MEDIUMTEXT type, for text up to 2^24 characters.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.MEDIUMTEXT (sqlalchemy.dialects.mysql.types._StringType)

method sqlalchemy.dialects.mysql.MEDIUMTEXT.__init__(**kwargs)¶

Construct a MEDIUMTEXT.

Parameters:

charset – Optional, a column-level character set for this string value. Takes precedence to ‘ascii’ or ‘unicode’ short-hand.
collation – Optional, a column-level collation for this string value. Takes precedence to ‘binary’ short-hand.
ascii – Defaults to False: short-hand for the latin1 character set, generates ASCII in schema.
unicode – Defaults to False: short-hand for the ucs2 character set, generates UNICODE in schema.
national – Optional. If true, use the server’s configured national character set.
binary – Defaults to False: short-hand, pick the binary collation type that matches the column’s character set. Generates BINARY in schema. This does not affect the type of data stored, only the collation of character data.

class sqlalchemy.dialects.mysql.NCHAR(length=None, **kwargs)¶

MySQL NCHAR type.

For fixed-length character data in the server’s configured national character set.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.NCHAR (sqlalchemy.dialects.mysql.types._StringType, sqlalchemy.types.NCHAR)

method sqlalchemy.dialects.mysql.NCHAR.__init__(length=None, **kwargs)¶

Construct an NCHAR.

Parameters:

length – Maximum data length, in characters.
binary – Optional, use the default binary collation for the national character set. This does not affect the type of data stored, use a BINARY type for binary data.
collation – Optional, request a particular collation. Must be compatible with the national character set.

class sqlalchemy.dialects.mysql.NUMERIC(precision=None, scale=None, asdecimal=True, **kw)¶

MySQL NUMERIC type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.NUMERIC (sqlalchemy.dialects.mysql.types._NumericType, sqlalchemy.types.NUMERIC)

method sqlalchemy.dialects.mysql.NUMERIC.__init__(precision=None, scale=None, asdecimal=True, **kw)¶

Construct a NUMERIC.

Parameters:

precision – Total digits in this number. If scale and precision are both None, values are stored to limits allowed by the server.
scale – The number of digits after the decimal point.
unsigned – a boolean, optional.
zerofill – Optional. If true, values will be stored as strings left-padded with zeros. Note that this does not effect the values returned by the underlying database API, which continue to be numeric.

class sqlalchemy.dialects.mysql.NVARCHAR(length=None, **kwargs)¶

MySQL NVARCHAR type.

For variable-length character data in the server’s configured national character set.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.NVARCHAR (sqlalchemy.dialects.mysql.types._StringType, sqlalchemy.types.NVARCHAR)

method sqlalchemy.dialects.mysql.NVARCHAR.__init__(length=None, **kwargs)¶

Construct an NVARCHAR.

Parameters:

length – Maximum data length, in characters.
binary – Optional, use the default binary collation for the national character set. This does not affect the type of data stored, use a BINARY type for binary data.
collation – Optional, request a particular collation. Must be compatible with the national character set.

class sqlalchemy.dialects.mysql.REAL(precision=None, scale=None, asdecimal=True, **kw)¶

MySQL REAL type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.REAL (sqlalchemy.dialects.mysql.types._FloatType, sqlalchemy.types.REAL)

method sqlalchemy.dialects.mysql.REAL.__init__(precision=None, scale=None, asdecimal=True, **kw)¶

Construct a REAL.

Note

The REAL type by default converts from float to Decimal, using a truncation that defaults to 10 digits. Specify either scale=n or decimal_return_scale=n in order to change this scale, or asdecimal=False to return values directly as Python floating points.

Parameters:

precision – Total digits in this number. If scale and precision are both None, values are stored to limits allowed by the server.
scale – The number of digits after the decimal point.
unsigned – a boolean, optional.
zerofill – Optional. If true, values will be stored as strings left-padded with zeros. Note that this does not effect the values returned by the underlying database API, which continue to be numeric.

class sqlalchemy.dialects.mysql.SET(*values, **kw)¶

MySQL SET type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.SET (sqlalchemy.dialects.mysql.enumerated._EnumeratedValues)

method sqlalchemy.dialects.mysql.SET.__init__(*values, **kw)¶

Construct a SET.

E.g.:

Column('myset', SET("foo", "bar", "baz"))

The list of potential values is required in the case that this set will be used to generate DDL for a table, or if the SET.retrieve_as_bitwise flag is set to True.

Parameters:

values – The range of valid values for this SET.
convert_unicode – Same flag as that of String.convert_unicode.
collation – same as that of String.collation
charset – same as that of VARCHAR.charset.
ascii – same as that of VARCHAR.ascii.
unicode – same as that of VARCHAR.unicode.
binary – same as that of VARCHAR.binary.
quoting –
Defaults to ‘auto’: automatically determine set value quoting. If all values are surrounded by the same quoting character, then use ‘quoted’ mode. Otherwise, use ‘unquoted’ mode.

’quoted’: values in enums are already quoted, they will be used directly when generating the schema - this usage is deprecated.

’unquoted’: values in enums are not quoted, they will be escaped and surrounded by single quotes when generating the schema.

Previous versions of this type always required manually quoted values to be supplied; future versions will always quote the string literals for you. This is a transitional option.

New in version 0.9.0.
retrieve_as_bitwise –
if True, the data for the set type will be persisted and selected using an integer value, where a set is coerced into a bitwise mask for persistence. MySQL allows this mode which has the advantage of being able to store values unambiguously, such as the blank string ''. The datatype will appear as the expression col + 0 in a SELECT statement, so that the value is coerced into an integer value in result sets. This flag is required if one wishes to persist a set that can store the blank string '' as a value.

Warning

When using SET.retrieve_as_bitwise, it is essential that the list of set values is expressed in the exact same order as exists on the MySQL database.

New in version 1.0.0.

class sqlalchemy.dialects.mysql.SMALLINT(display_width=None, **kw)¶

MySQL SMALLINTEGER type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.SMALLINT (sqlalchemy.dialects.mysql.types._IntegerType, sqlalchemy.types.SMALLINT)

method sqlalchemy.dialects.mysql.SMALLINT.__init__(display_width=None, **kw)¶

Construct a SMALLINTEGER.

Parameters:

display_width – Optional, maximum display width for this number.
unsigned – a boolean, optional.
zerofill – Optional. If true, values will be stored as strings left-padded with zeros. Note that this does not effect the values returned by the underlying database API, which continue to be numeric.

class sqlalchemy.dialects.mysql.TEXT(length=None, **kw)¶

MySQL TEXT type, for text up to 2^16 characters.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.TEXT (sqlalchemy.dialects.mysql.types._StringType, sqlalchemy.types.TEXT)

method sqlalchemy.dialects.mysql.TEXT.__init__(length=None, **kw)¶

Construct a TEXT.

Parameters:

length – Optional, if provided the server may optimize storage by substituting the smallest TEXT type sufficient to store length characters.
charset – Optional, a column-level character set for this string value. Takes precedence to ‘ascii’ or ‘unicode’ short-hand.
collation – Optional, a column-level collation for this string value. Takes precedence to ‘binary’ short-hand.
ascii – Defaults to False: short-hand for the latin1 character set, generates ASCII in schema.
unicode – Defaults to False: short-hand for the ucs2 character set, generates UNICODE in schema.
national – Optional. If true, use the server’s configured national character set.
binary – Defaults to False: short-hand, pick the binary collation type that matches the column’s character set. Generates BINARY in schema. This does not affect the type of data stored, only the collation of character data.

class sqlalchemy.dialects.mysql.TIME(timezone=False, fsp=None)¶

MySQL TIME type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.TIME (sqlalchemy.types.TIME)

method sqlalchemy.dialects.mysql.TIME.__init__(timezone=False, fsp=None)¶

Construct a MySQL TIME type.

Parameters:

timezone – not used by the MySQL dialect.
fsp –
fractional seconds precision value. MySQL 5.6 supports storage of fractional seconds; this parameter will be used when emitting DDL for the TIME type.

Note

DBAPI driver support for fractional seconds may be limited; current support includes MySQL Connector/Python.

class sqlalchemy.dialects.mysql.TIMESTAMP(timezone=False, fsp=None)¶

MySQL TIMESTAMP type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.TIMESTAMP (sqlalchemy.types.TIMESTAMP)

method sqlalchemy.dialects.mysql.TIMESTAMP.__init__(timezone=False, fsp=None)¶

Construct a MySQL TIMESTAMP type.

Parameters:

timezone – not used by the MySQL dialect.
fsp –
fractional seconds precision value. MySQL 5.6.4 supports storage of fractional seconds; this parameter will be used when emitting DDL for the TIMESTAMP type.

Note

DBAPI driver support for fractional seconds may be limited; current support includes MySQL Connector/Python.

class sqlalchemy.dialects.mysql.TINYBLOB(length=None)¶: MySQL TINYBLOB type, for binary data up to 2^8 bytes.

Class signature

class sqlalchemy.dialects.mysql.TINYBLOB (sqlalchemy.types._Binary)

class sqlalchemy.dialects.mysql.TINYINT(display_width=None, **kw)¶

MySQL TINYINT type.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.TINYINT (sqlalchemy.dialects.mysql.types._IntegerType)

method sqlalchemy.dialects.mysql.TINYINT.__init__(display_width=None, **kw)¶

Construct a TINYINT.

Parameters:

display_width – Optional, maximum display width for this number.
unsigned – a boolean, optional.
zerofill – Optional. If true, values will be stored as strings left-padded with zeros. Note that this does not effect the values returned by the underlying database API, which continue to be numeric.

class sqlalchemy.dialects.mysql.TINYTEXT(**kwargs)¶

MySQL TINYTEXT type, for text up to 2^8 characters.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.TINYTEXT (sqlalchemy.dialects.mysql.types._StringType)

method sqlalchemy.dialects.mysql.TINYTEXT.__init__(**kwargs)¶

Construct a TINYTEXT.

Parameters:

charset – Optional, a column-level character set for this string value. Takes precedence to ‘ascii’ or ‘unicode’ short-hand.
collation – Optional, a column-level collation for this string value. Takes precedence to ‘binary’ short-hand.
ascii – Defaults to False: short-hand for the latin1 character set, generates ASCII in schema.
unicode – Defaults to False: short-hand for the ucs2 character set, generates UNICODE in schema.
national – Optional. If true, use the server’s configured national character set.
binary – Defaults to False: short-hand, pick the binary collation type that matches the column’s character set. Generates BINARY in schema. This does not affect the type of data stored, only the collation of character data.

class sqlalchemy.dialects.mysql.VARBINARY(length=None)¶: The SQL VARBINARY type.

Class signature

class sqlalchemy.dialects.mysql.VARBINARY (sqlalchemy.types._Binary)

class sqlalchemy.dialects.mysql.VARCHAR(length=None, **kwargs)¶

MySQL VARCHAR type, for variable-length character data.

Members

__init__()

Class signature

class sqlalchemy.dialects.mysql.VARCHAR (sqlalchemy.dialects.mysql.types._StringType, sqlalchemy.types.VARCHAR)

method sqlalchemy.dialects.mysql.VARCHAR.__init__(length=None, **kwargs)¶

Construct a VARCHAR.

Parameters:

charset – Optional, a column-level character set for this string value. Takes precedence to ‘ascii’ or ‘unicode’ short-hand.
collation – Optional, a column-level collation for this string value. Takes precedence to ‘binary’ short-hand.
ascii – Defaults to False: short-hand for the latin1 character set, generates ASCII in schema.
unicode – Defaults to False: short-hand for the ucs2 character set, generates UNICODE in schema.
national – Optional. If true, use the server’s configured national character set.
binary – Defaults to False: short-hand, pick the binary collation type that matches the column’s character set. Generates BINARY in schema. This does not affect the type of data stored, only the collation of character data.

class sqlalchemy.dialects.mysql.YEAR(display_width=None)¶: MySQL YEAR type, for single byte storage of years 1901-2155.

Class signature

class sqlalchemy.dialects.mysql.YEAR (sqlalchemy.types.TypeEngine)

MySQL DML Constructs¶

Object Name	Description
insert(table[, values, inline, bind, ...], **dialect_kw)	Construct an `Insert` object.
Insert	MySQL-specific implementation of INSERT.

function sqlalchemy.dialects.mysql.insert(table, values=None, inline=False, bind=None, prefixes=None, returning=None, return_defaults=False, **dialect_kw)¶

Construct an Insert object.

This documentation is inherited from sqlalchemy.sql.expression.insert(); this constructor, sqlalchemy.dialects.mysql.insert(), creates a sqlalchemy.dialects.mysql.Insert object. See that class for additional details describing this subclass.

Similar functionality is available via the TableClause.insert() method on Table.

Parameters:

table – TableClause which is the subject of the insert.
values – collection of values to be inserted; see Insert.values() for a description of allowed formats here. Can be omitted entirely; a Insert construct will also dynamically render the VALUES clause at execution time based on the parameters passed to Connection.execute().
inline – if True, no attempt will be made to retrieve the SQL-generated default values to be provided within the statement; in particular, this allows SQL expressions to be rendered ‘inline’ within the statement without the need to pre-execute them beforehand; for backends that support “returning”, this turns off the “implicit returning” feature for the statement.

If both values and compile-time bind parameters are present, the compile-time bind parameters override the information specified within values on a per-key basis.

The keys within values can be either Column objects or their string identifiers. Each key may reference one of:

a literal data value (i.e. string, number, etc.);
a Column object;
a SELECT statement.

If a SELECT statement is specified which references this INSERT statement’s table, the statement will be correlated against the INSERT statement.

See also

Insert Expressions - SQL Expression Tutorial

Inserts, Updates and Deletes - SQL Expression Tutorial

class sqlalchemy.dialects.mysql.Insert(table, values=None, inline=False, bind=None, prefixes=None, returning=None, return_defaults=False, **dialect_kw)¶

MySQL-specific implementation of INSERT.

Adds methods for MySQL-specific syntaxes such as ON DUPLICATE KEY UPDATE.

The Insert object is created using the sqlalchemy.dialects.mysql.insert() function.

New in version 1.2.

Members

inserted, on_duplicate_key_update()

Class signature

class sqlalchemy.dialects.mysql.Insert (sqlalchemy.sql.expression.Insert)

attribute sqlalchemy.dialects.mysql.Insert.inserted¶

Provide the “inserted” namespace for an ON DUPLICATE KEY UPDATE statement

MySQL’s ON DUPLICATE KEY UPDATE clause allows reference to the row that would be inserted, via a special function called VALUES(). This attribute provides all columns in this row to be referenceable such that they will render within a VALUES() function inside the ON DUPLICATE KEY UPDATE clause. The attribute is named .inserted so as not to conflict with the existing Insert.values() method.

See also

INSERT…ON DUPLICATE KEY UPDATE (Upsert) - example of how to use Insert.inserted

method sqlalchemy.dialects.mysql.Insert.on_duplicate_key_update(*args, **kw)¶

Specifies the ON DUPLICATE KEY UPDATE clause.

Parameters:: **kw – Column keys linked to UPDATE values. The values may be any SQL expression or supported literal Python values.

Warning

This dictionary does not take into account Python-specified default UPDATE values or generation functions, e.g. those specified using Column.onupdate. These values will not be exercised for an ON DUPLICATE KEY UPDATE style of UPDATE, unless values are manually specified here.

Parameters:

*args –

As an alternative to passing key/value parameters, a dictionary or list of 2-tuples can be passed as a single positional argument.

Passing a single dictionary is equivalent to the keyword argument form:

insert().on_duplicate_key_update({"name": "some name"})

Passing a list of 2-tuples indicates that the parameter assignments in the UPDATE clause should be ordered as sent, in a manner similar to that described for the Update construct overall in Parameter-Ordered Updates:

insert().on_duplicate_key_update(
    [("name", "some name"), ("value", "some value")])

Changed in version 1.3: parameters can be specified as a dictionary or list of 2-tuples; the latter form provides for parameter ordering.

New in version 1.2.

See also

INSERT…ON DUPLICATE KEY UPDATE (Upsert)

mysqlclient (fork of MySQL-Python)¶

Support for the MySQL database via the mysqlclient (maintained fork of MySQL-Python) driver.

DBAPI¶

Documentation and download information (if applicable) for mysqlclient (maintained fork of MySQL-Python) is available at: https://pypi.org/project/mysqlclient/

Connecting¶

Connect String:

mysql+mysqldb://<user>:<password>@<host>[:<port>]/<dbname>

Driver Status¶

The mysqlclient DBAPI is a maintained fork of the MySQL-Python DBAPI that is no longer maintained. mysqlclient supports Python 2 and Python 3 and is very stable.

Unicode¶

Please see Unicode for current recommendations on unicode handling.

Using MySQLdb with Google Cloud SQL¶

Google Cloud SQL now recommends use of the MySQLdb dialect. Connect using a URL like the following:

mysql+mysqldb://root@/<dbname>?unix_socket=/cloudsql/<projectid>:<instancename>

Server Side Cursors¶

The mysqldb dialect supports server-side cursors. See Server Side Cursors.

PyMySQL¶

Support for the MySQL database via the PyMySQL driver.

DBAPI¶

Documentation and download information (if applicable) for PyMySQL is available at: https://pymysql.readthedocs.io/

Connecting¶

Connect String:

mysql+pymysql://<username>:<password>@<host>/<dbname>[?<options>]

Unicode¶

Please see Unicode for current recommendations on unicode handling.

MySQL-Python Compatibility¶

The pymysql DBAPI is a pure Python port of the MySQL-python (MySQLdb) driver, and targets 100% compatibility. Most behavioral notes for MySQL-python apply to the pymysql driver as well.

MySQL-Connector¶

Support for the MySQL database via the MySQL Connector/Python driver.

DBAPI¶

Documentation and download information (if applicable) for MySQL Connector/Python is available at: https://pypi.org/project/mysql-connector-python/

Connecting¶

Connect String:

mysql+mysqlconnector://<user>:<password>@<host>[:<port>]/<dbname>

Note

The MySQL Connector/Python DBAPI has had many issues since its release, some of which may remain unresolved, and the mysqlconnector dialect is not tested as part of SQLAlchemy’s continuous integration. The recommended MySQL dialects are mysqlclient and PyMySQL.

cymysql¶

Support for the MySQL database via the CyMySQL driver.

DBAPI¶

Documentation and download information (if applicable) for CyMySQL is available at: https://github.com/nakagami/CyMySQL

Connecting¶

Connect String:

mysql+cymysql://<username>:<password>@<host>/<dbname>[?<options>]

Note

The CyMySQL dialect is not tested as part of SQLAlchemy’s continuous integration and may have unresolved issues. The recommended MySQL dialects are mysqlclient and PyMySQL.

OurSQL¶

Support for the MySQL database via the OurSQL driver.

DBAPI¶

Documentation and download information (if applicable) for OurSQL is available at: http://packages.python.org/oursql/

Connecting¶

Connect String:

mysql+oursql://<user>:<password>@<host>[:<port>]/<dbname>

Note

The OurSQL MySQL dialect is legacy and is no longer supported upstream, and is not tested as part of SQLAlchemy’s continuous integration. The recommended MySQL dialects are mysqlclient and PyMySQL.

Unicode¶

Please see Unicode for current recommendations on unicode handling.

Google App Engine¶

Support for the MySQL database via the Google Cloud SQL driver.

This dialect is based primarily on the mysqldb dialect with minimal changes.

Deprecated since version 1.0: This dialect is no longer necessary for Google Cloud SQL; the MySQLdb dialect can be used directly. Cloud SQL now recommends creating connections via the mysql dialect using the URL format

mysql+mysqldb://root@/<dbname>?unix_socket=/cloudsql/<projectid>:<instancename>

DBAPI¶

Documentation and download information (if applicable) for Google Cloud SQL is available at: https://developers.google.com/appengine/docs/python/cloud-sql/developers-guide

Connecting¶

Connect String:

mysql+gaerdbms:///<dbname>?instance=<instancename>

Pooling¶

Google App Engine connections appear to be randomly recycled, so the dialect does not pool connections. The NullPool implementation is installed within the Engine by default.

pyodbc¶

Support for the MySQL database via the PyODBC driver.

Note

The PyODBC for MySQL dialect is not well supported, and is subject to unresolved character encoding issues which exist within the current ODBC drivers available. (see http://code.google.com/p/pyodbc/issues/detail?id=25). Other dialects for MySQL are recommended.

DBAPI¶

Documentation and download information (if applicable) for PyODBC is available at: http://pypi.python.org/pypi/pyodbc/

Connecting¶

Connect String:

mysql+pyodbc://<username>:<password>@<dsnname>

Pass through exact pyodbc connection string:

import urllib
connection_string = (
    'DRIVER=MySQL ODBC 8.0 ANSI Driver;'
    'SERVER=localhost;'
    'PORT=3307;'
    'DATABASE=mydb;'
    'UID=root;'
    'PWD=(whatever);'
    'charset=utf8mb4;'
)
params = urllib.parse.quote_plus(connection_string)
connection_uri = "mysql+pyodbc:///?odbc_connect=%s" % params

zxjdbc¶

Support for the MySQL database via the zxjdbc for Jython driver.

Note

Jython is not supported by current versions of SQLAlchemy. The zxjdbc dialect should be considered as experimental.

DBAPI¶

Drivers for this database are available at: http://dev.mysql.com/downloads/connector/j/

Connecting¶

Connect String:

mysql+zxjdbc://<user>:<password>@<hostname>[:<port>]/<database>

Character Sets¶

SQLAlchemy zxjdbc dialects pass unicode straight through to the zxjdbc/JDBC layer. To allow multiple character sets to be sent from the MySQL Connector/J JDBC driver, by default SQLAlchemy sets its characterEncoding connection property to UTF-8. It may be overridden via a create_engine URL parameter.

SQLAlchemy 1.3 Documentation

SQLAlchemy 1.3 Documentation

Dialects

MySQL¶

DBAPI Support¶

Supported Versions and Features¶

Connection Timeouts and Disconnects¶

CREATE TABLE arguments including Storage Engines¶

Case Sensitivity and Table Reflection¶

Transaction Isolation Level¶

AUTO_INCREMENT Behavior¶

Server Side Cursors¶

Unicode¶

Charset Selection¶

Dealing with Binary Data Warnings and Unicode¶

ANSI Quoting Style¶

MySQL SQL Extensions¶

INSERT…ON DUPLICATE KEY UPDATE (Upsert)¶

rowcount Support¶

CAST Support¶

MySQL Specific Index Options¶

Index Length¶

Index Prefixes¶

Index Types¶

Index Parsers¶

MySQL Foreign Keys¶

Foreign Key Arguments to Avoid¶

Reflection of Foreign Key Constraints¶

MySQL Unique Constraints and Reflection¶

TIMESTAMP / DATETIME issues¶

Rendering ON UPDATE CURRENT TIMESTAMP for MySQL’s explicit_defaults_for_timestamp¶

TIMESTAMP Columns and NULL¶

MySQL Data Types¶

MySQL DML Constructs¶

mysqlclient (fork of MySQL-Python)¶

DBAPI¶

Connecting¶

Driver Status¶

Unicode¶

Using MySQLdb with Google Cloud SQL¶

Server Side Cursors¶

PyMySQL¶

DBAPI¶

Connecting¶

Unicode¶

MySQL-Python Compatibility¶

MySQL-Connector¶

DBAPI¶

Connecting¶

cymysql¶

DBAPI¶

Connecting¶

OurSQL¶

DBAPI¶

Connecting¶

Unicode¶

Google App Engine¶

DBAPI¶

Connecting¶

Pooling¶

pyodbc¶

DBAPI¶

Connecting¶

zxjdbc¶

DBAPI¶

Connecting¶

Character Sets¶