Support for the MySQL database.

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.

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.

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 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().

Unicode¶

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

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

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

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

# 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")

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 mysql.dml.insert() function, which provides the generative method 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 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()),
    ],
)

In order to refer to the proposed insertion row, the special alias inserted is available as an attribute on the mysql.dml.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>).

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.

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('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})

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

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

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

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

MySQL Foreign Keys¶

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

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)

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 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
)

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:

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

Bases: sqlalchemy.dialects.mysql.types._IntegerType, sqlalchemy.types.BIGINT

MySQL BIGINTEGER type.

__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)¶

Bases: sqlalchemy.types._Binary

The SQL BINARY type.

__init__(length=None)¶

inherited from the __init__() method of _Binary

Initialize self. See help(type(self)) for accurate signature.

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

Bases: sqlalchemy.types.TypeEngine

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.

__init__(length=None)¶

Construct a BIT.

Parameters:	length¶ – Optional, number of bits.

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

Bases: sqlalchemy.types.LargeBinary

The SQL BLOB type.

__init__(length=None)¶

inherited from the __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)¶

Bases: sqlalchemy.types.Boolean

The SQL BOOLEAN type.

__init__(create_constraint=True, name=None, _create_events=True)¶

inherited from the __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)¶

Bases: sqlalchemy.dialects.mysql.types._StringType, sqlalchemy.types.CHAR

MySQL CHAR type, for fixed-length character data.

__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¶

Bases: sqlalchemy.types.Date

The SQL DATE type.

__init__¶

inherited from the __init__ attribute of object

Initialize self. See help(type(self)) for accurate signature.

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

Bases: sqlalchemy.types.DATETIME

MySQL DATETIME type.

__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)¶

Bases: sqlalchemy.dialects.mysql.types._NumericType, sqlalchemy.types.DECIMAL

MySQL DECIMAL type.

__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)¶

Bases: sqlalchemy.dialects.mysql.types._FloatType

MySQL DOUBLE type.

__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)¶

Bases: sqlalchemy.types.NativeForEmulated, sqlalchemy.types.Enum, sqlalchemy.dialects.mysql.enumerated._EnumeratedValues

MySQL ENUM type.

__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)¶

Bases: sqlalchemy.dialects.mysql.types._FloatType, sqlalchemy.types.FLOAT

MySQL FLOAT type.

__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)¶

Bases: sqlalchemy.dialects.mysql.types._IntegerType, sqlalchemy.types.INTEGER

MySQL INTEGER type.

__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)¶

Bases: sqlalchemy.types.JSON

MySQL JSON type.

MySQL supports JSON as of version 5.7. Note that MariaDB does not support JSON at the time of this writing.

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

New in version 1.1.

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

Bases: sqlalchemy.types._Binary

MySQL LONGBLOB type, for binary data up to 2^32 bytes.

__init__(length=None)¶

inherited from the __init__() method of _Binary

Initialize self. See help(type(self)) for accurate signature.

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

Bases: sqlalchemy.dialects.mysql.types._StringType

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

__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)¶

Bases: sqlalchemy.types._Binary

MySQL MEDIUMBLOB type, for binary data up to 2^24 bytes.

__init__(length=None)¶

inherited from the __init__() method of _Binary

Initialize self. See help(type(self)) for accurate signature.

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

Bases: sqlalchemy.dialects.mysql.types._IntegerType

MySQL MEDIUMINTEGER type.

__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)¶

Bases: sqlalchemy.dialects.mysql.types._StringType

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

__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)¶

Bases: sqlalchemy.dialects.mysql.types._StringType, sqlalchemy.types.NCHAR

MySQL NCHAR type.

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

__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)¶

Bases: sqlalchemy.dialects.mysql.types._NumericType, sqlalchemy.types.NUMERIC

MySQL NUMERIC type.

__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)¶

Bases: sqlalchemy.dialects.mysql.types._StringType, sqlalchemy.types.NVARCHAR

MySQL NVARCHAR type.

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

__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)¶

Bases: sqlalchemy.dialects.mysql.types._FloatType, sqlalchemy.types.REAL

MySQL REAL type.

__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)¶

Bases: sqlalchemy.dialects.mysql.enumerated._EnumeratedValues

MySQL SET type.

__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 mysql.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)¶

Bases: sqlalchemy.dialects.mysql.types._IntegerType, sqlalchemy.types.SMALLINT

MySQL SMALLINTEGER type.

__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)¶

Bases: sqlalchemy.dialects.mysql.types._StringType, sqlalchemy.types.TEXT

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

__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)¶

Bases: sqlalchemy.types.TIME

MySQL TIME type.

__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)¶

Bases: sqlalchemy.types.TIMESTAMP

MySQL TIMESTAMP type.

__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)¶

Bases: sqlalchemy.types._Binary

MySQL TINYBLOB type, for binary data up to 2^8 bytes.

__init__(length=None)¶

inherited from the __init__() method of _Binary

Initialize self. See help(type(self)) for accurate signature.

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

Bases: sqlalchemy.dialects.mysql.types._IntegerType

MySQL TINYINT type.

__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)¶

Bases: sqlalchemy.dialects.mysql.types._StringType

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

__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)¶

Bases: sqlalchemy.types._Binary

The SQL VARBINARY type.

__init__(length=None)¶

inherited from the __init__() method of _Binary

Initialize self. See help(type(self)) for accurate signature.

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

Bases: sqlalchemy.dialects.mysql.types._StringType, sqlalchemy.types.VARCHAR

MySQL VARCHAR type, for variable-length character data.

__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)¶

Bases: sqlalchemy.types.TypeEngine

MySQL YEAR type, for single byte storage of years 1901-2155.

__init__(display_width=None)¶

Initialize self. See help(type(self)) for accurate signature.

MySQL DML Constructs¶

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

Construct a new Insert object.

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

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

Bases: sqlalchemy.sql.expression.Insert

MySQL-specific implementation of INSERT.

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

New in version 1.2.

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

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.

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

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

PyMySQL¶

Support for the MySQL database via the PyMySQL driver.

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

MySQL-Connector¶

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

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

cymysql¶

Support for the MySQL database via the CyMySQL driver.

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

OurSQL¶

Support for the MySQL database via the OurSQL driver.

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

Google App Engine¶

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

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

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

pyodbc¶

Support for the MySQL database via the PyODBC driver.

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

zxjdbc¶

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

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