SQLAlchemy 0.6.1 Documentation

Version: 0.6.1 Last Updated: 07/25/2016 21:14:41
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MySQL

MySQL

Support for the MySQL database.

Supported Versions and Features

SQLAlchemy supports 6 major MySQL versions: 3.23, 4.0, 4.1, 5.0, 5.1 and 6.0, with capabilities increasing with more modern servers.

Versions 4.1 and higher support the basic SQL functionality that SQLAlchemy uses in the ORM and SQL expressions. These versions pass the applicable tests in the suite 100%. 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.

Most available DBAPI drivers are supported; see below.

Feature Minimum Version
sqlalchemy.orm 4.1.1
Table Reflection 3.23.x
DDL Generation 4.1.1
utf8/Full Unicode Connections 4.1.1
Transactions 3.23.15
Two-Phase Transactions 5.0.3
Nested Transactions 5.0.3

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

Connecting

See the API documentation on individual drivers for details on connecting.

Data Types

All of MySQL’s standard types are supported. These can also be specified within table metadata, for the purpose of issuing CREATE TABLE statements which include MySQL-specific extensions. The types are available from the module, as in:

from sqlalchemy.dialects import mysql

Table('mytable', metadata,
      Column('id', Integer, primary_key=True),
      Column('ittybittyblob', mysql.TINYBLOB),
      Column('biggy', mysql.BIGINT(unsigned=True)))

See the API documentation on specific column types for further details.

Connection Timeouts

MySQL features an automatic connection close behavior, for connections that have been idle for eight hours or more. To circumvent having this issue, use the pool_recycle option which controls the maximum age of any connection:

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

Storage Engines

Most MySQL server installations have a default table type of MyISAM, a non-transactional table type. During a transaction, non-transactional storage engines do not participate and continue to store table changes in autocommit mode. For fully atomic transactions, all participating tables must use a transactional engine such as InnoDB, Falcon, SolidDB, PBXT, etc.

Storage engines can be elected when creating tables in SQLAlchemy by supplying a mysql_engine='whatever' to the Table constructor. Any MySQL table creation option can be specified in this syntax:

Table('mytable', metadata,
      Column('data', String(32)),
      mysql_engine='InnoDB',
      mysql_charset='utf8'
     )

Keys

Not all MySQL storage engines support foreign keys. For MyISAM and similar engines, 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
     )

When creating tables, SQLAlchemy will automatically set AUTO_INCREMENT` on an integer primary key column:

>>> 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 supplying autoincrement=False to the 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)
     )

SQL Mode

MySQL SQL modes are supported. Modes that enable ANSI_QUOTES (such as ANSI) require an engine option to modify SQLAlchemy’s quoting style. When using an ANSI-quoting mode, supply use_ansiquotes=True when creating your Engine:

create_engine('mysql://localhost/test', use_ansiquotes=True)

This is an engine-wide option and is not toggleable on a per-connection basis. SQLAlchemy does not presume to SET sql_mode for you with this option. For the best performance, set the quoting style server-wide in my.cnf or by supplying --sql-mode to mysqld. You can also use a sqlalchemy.pool.Pool listener hook to issue a SET SESSION sql_mode='...' on connect to configure each connection.

If you do not specify use_ansiquotes, the regular MySQL quoting style is used by default.

If you do issue a SET sql_mode through SQLAlchemy, the dialect must be updated if the quoting style is changed. Again, this change will affect all connections:

connection.execute('SET sql_mode="ansi"')
connection.dialect.use_ansiquotes = True

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.

  • SELECT pragma:

    select(..., prefixes=['HIGH_PRIORITY', 'SQL_SMALL_RESULT'])

  • UPDATE with LIMIT:

    update(..., mysql_limit=10)

Troubleshooting

If you have problems that seem server related, first check that you are using the most recent stable MySQL-Python package available. The Database Notes page on the wiki at http://www.sqlalchemy.org is a good resource for timely information affecting MySQL in SQLAlchemy.

MySQL Column Types

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

Bases: sqlalchemy.dialects.mysql.base._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.DECIMAL(precision=None, scale=None, asdecimal=True, **kw)

Bases: sqlalchemy.dialects.mysql.base._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.base._FloatType

MySQL DOUBLE type.

__init__(precision=None, scale=None, asdecimal=True, **kw)

Construct a DOUBLE.

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.REAL(precision=None, scale=None, asdecimal=True, **kw)

Bases: sqlalchemy.dialects.mysql.base._FloatType

MySQL REAL type.

__init__(precision=None, scale=None, asdecimal=True, **kw)

Construct a REAL.

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.FLOAT(precision=None, scale=None, asdecimal=False, **kw)

Bases: sqlalchemy.dialects.mysql.base._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.base._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.BIGINT(display_width=None, **kw)

Bases: sqlalchemy.dialects.mysql.base._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.MEDIUMINT(display_width=None, **kw)

Bases: sqlalchemy.dialects.mysql.base._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.TINYINT(display_width=None, **kw)

Bases: sqlalchemy.dialects.mysql.base._IntegerType

MySQL TINYINT type.

__init__(display_width=None, **kw)

Construct a TINYINT.

Note: following the usual MySQL conventions, TINYINT(1) columns reflected during Table(..., autoload=True) are treated as Boolean columns.

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.SMALLINT(display_width=None, **kw)

Bases: sqlalchemy.dialects.mysql.base._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.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.

Parameter:length – Optional, number of bits.
class sqlalchemy.dialects.mysql.DATETIME(timezone=False)

Bases: sqlalchemy.types.DateTime

The SQL DATETIME type.

__init__(timezone=False)
class sqlalchemy.dialects.mysql.DATE(*args, **kwargs)

Bases: sqlalchemy.types.Date

The SQL DATE type.

__init__(*args, **kwargs)
class sqlalchemy.dialects.mysql.TIME(timezone=False)

Bases: sqlalchemy.types.Time

The SQL TIME type.

__init__(timezone=False)
class sqlalchemy.dialects.mysql.TIMESTAMP(timezone=False)

Bases: sqlalchemy.types.TIMESTAMP

MySQL TIMESTAMP type.

__init__(timezone=False)
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)
class sqlalchemy.dialects.mysql.TEXT(length=None, **kw)

Bases: sqlalchemy.dialects.mysql.base._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.TINYTEXT(**kwargs)

Bases: sqlalchemy.dialects.mysql.base._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.MEDIUMTEXT(**kwargs)

Bases: sqlalchemy.dialects.mysql.base._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.LONGTEXT(**kwargs)

Bases: sqlalchemy.dialects.mysql.base._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.VARCHAR(length=None, **kwargs)

Bases: sqlalchemy.dialects.mysql.base._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.CHAR(length, **kwargs)

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

MySQL CHAR type, for fixed-length character data.

__init__(length, **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.NVARCHAR(length=None, **kwargs)

Bases: sqlalchemy.dialects.mysql.base._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.NCHAR(length=None, **kwargs)

Bases: sqlalchemy.dialects.mysql.base._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. Arguments are:

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.VARBINARY(length=None)

Bases: sqlalchemy.types._Binary

The SQL VARBINARY type.

__init__(length=None)
class sqlalchemy.dialects.mysql.BINARY(length=None)

Bases: sqlalchemy.types._Binary

The SQL BINARY type.

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

Bases: sqlalchemy.types.LargeBinary

The SQL BLOB type.

__init__(length=None)

Construct a LargeBinary type.

Parameter:length – optional, a length for the column for use in DDL statements, for those BLOB types that accept a length (i.e. MySQL). It does not produce a small BINARY/VARBINARY type - use the BINARY/VARBINARY types specifically for those. May be safely omitted if no CREATE TABLE will be issued. Certain databases may require a length for use in DDL, and will raise an exception when the CREATE TABLE DDL is issued.
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)
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)
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)
class sqlalchemy.dialects.mysql.ENUM(*enums, **kw)

Bases: sqlalchemy.types.Enum, sqlalchemy.dialects.mysql.base._StringType

MySQL ENUM type.

__init__(*enums, **kw)

Construct an ENUM.

Example:

Column(‘myenum’, MSEnum(“foo”, “bar”, “baz”))

Arguments are:

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).
  • strict – Defaults to False: ensure that a given value is in this ENUM’s range of permissible values when inserting or updating rows. Note that MySQL will not raise a fatal error if you attempt to store an out of range value- an alternate value will be stored instead. (See MySQL ENUM documentation.)
  • 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.SET(*values, **kw)

Bases: sqlalchemy.dialects.mysql.base._StringType

MySQL SET type.

__init__(*values, **kw)

Construct a SET.

Example:

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

Arguments are:

Parameters:
  • values – The range of valid values for this SET. Values will be used exactly as they appear when generating schemas. Strings must be quoted, as in the example above. Single-quotes are suggested for ANSI compatibility and are required for portability to servers with ANSI_QUOTES enabled.
  • 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.
class sqlalchemy.dialects.mysql.BOOLEAN(create_constraint=True, name=None)

Bases: sqlalchemy.types.Boolean

The SQL BOOLEAN type.

__init__(create_constraint=True, name=None)

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.

MySQL-Python Notes

Support for the MySQL database via the MySQL-python adapter.

MySQL-Python is available at:

http://sourceforge.net/projects/mysql-python

At least version 1.2.1 or 1.2.2 should be used.

Connecting

Connect string format:

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

Character Sets

Many MySQL server installations default to a latin1 encoding for client connections. All data sent through the connection will be converted into latin1, even if you have utf8 or another character set on your tables and columns. With versions 4.1 and higher, you can change the connection character set either through server configuration or by including the charset parameter in the URL used for create_engine. The charset option is passed through to MySQL-Python and has the side-effect of also enabling use_unicode in the driver by default. For regular encoded strings, also pass use_unicode=0 in the connection arguments:

# set client encoding to utf8; all strings come back as unicode
create_engine('mysql+mysqldb:///mydb?charset=utf8')

# set client encoding to utf8; all strings come back as utf8 str
create_engine('mysql+mysqldb:///mydb?charset=utf8&use_unicode=0')

Known Issues

MySQL-python at least as of version 1.2.2 has a serious memory leak related to unicode conversion, a feature which is disabled via use_unicode=0. The recommended connection form with SQLAlchemy is:

engine = create_engine('mysql://scott:tiger@localhost/test?charset=utf8&use_unicode=0', pool_recycle=3600)

OurSQL Notes

Support for the MySQL database via the oursql adapter.

OurSQL is available at:

http://packages.python.org/oursql/

Connecting

Connect string format:

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

Character Sets

oursql defaults to using utf8 as the connection charset, but other encodings may be used instead. Like the MySQL-Python driver, unicode support can be completely disabled:

# oursql sets the connection charset to utf8 automatically; all strings come
# back as utf8 str
create_engine('mysql+oursql:///mydb?use_unicode=0')

To not automatically use utf8 and instead use whatever the connection defaults to, there is a separate parameter:

# use the default connection charset; all strings come back as unicode
create_engine('mysql+oursql:///mydb?default_charset=1')

# use latin1 as the connection charset; all strings come back as unicode
create_engine('mysql+oursql:///mydb?charset=latin1')

MySQL-Connector Notes

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

MySQL Connector/Python is available at:

https://launchpad.net/myconnpy

Connecting

Connect string format:

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

pyodbc Notes

Support for the MySQL database via the pyodbc adapter.

pyodbc is available at:

http://pypi.python.org/pypi/pyodbc/

Connecting

Connect string:

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

Limitations

The mysql-pyodbc dialect 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). Consider usage of OurSQL, MySQLdb, or MySQL-connector/Python.

zxjdbc Notes

Support for the MySQL database via Jython’s zxjdbc JDBC connector.

JDBC Driver

The official MySQL JDBC driver is at http://dev.mysql.com/downloads/connector/j/.

Connecting

Connect string format:

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 overriden via a create_engine URL parameter.

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