src/site/sphinx/databases/mysql.rst

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.. _`MySQL`: http://www.mysql.com/products/mysql/
.. _`MySQL Reference Manual`: http://dev.mysql.com/doc/mysql/en/index.html

MySQL
=====

`MySQL`_ is supported from version 3.23 onwards. Note that the major versions
(3, 4, 5) differ in their datatype support. The supported SQL syntax and datatypes
can be found in the `MySQL Reference Manual`_.

DdlUtils provides two platforms, one for MySql versions 3 and 4, and one for MySql version 5 and above.
The latter implements some aspects of reading back a model from the database differently to address
some changes in MySql 5.

Constraints
-----------

Platform identifier
  | ``MySQL`` for MySql 3 and 4
  | ``MySQL5`` for MySql 5

Recognized JDBC drivers
  | ``com.mysql.jdbc.Driver``
  | ``org.gjt.mm.mysql.Driver``

Recognized JDBC sub protocols
  ``jdbc:mysql``

Supports SQL comments
  yes

Supports delimited identifiers
  yes

Maximum identifier length
  64

Supports default values for ``LONG`` types
  no

Supports non-unique indices
  yes

Supports non-primary key columns as identity columns
  no

Allows ``INSERT``/``UPDATE`` statements to set values for identity columns
  yes

DdlUtils uses sequences for identity columns
  no

DdlUtils can read back the auto-generated value of an identity column
  yes

DdlUtils can create a database via JDBC
  no

DdlUtils can drop a database via JDBC
  no

Datatypes
---------

+-----------------+--------------------------------+---------------------------------------------+
|JDBC Type        |Database Type                   |Additional comments                          |
+=================+================================+=============================================+
|``ARRAY``        |``LONGBLOB``                    |Will be read back as ``LONGVARBINARY``       |
+-----------------+--------------------------------+---------------------------------------------+
|``BIGINT``       |``BIGINT``                      |                                             |
+-----------------+--------------------------------+---------------------------------------------+
|``BINARY``       |``BINARY``                      |                                             |
+-----------------+--------------------------------+---------------------------------------------+
|``BIT``          |``TINYINT(1)``                  |MySql has no native boolean type.            |
+-----------------+--------------------------------+---------------------------------------------+
|``BLOB``         |``LONGBLOB``                    |Will be read back as ``LONGVARBINARY``       |
+-----------------+--------------------------------+---------------------------------------------+
|``BOOLEAN``      |``TINYINT(1)``                  |MySql has no native boolean type.            |
|                 |                                |Will be read back as ``BIT``                 |
+-----------------+--------------------------------+---------------------------------------------+
|``CHAR``         |``CHAR``                        |                                             |
+-----------------+--------------------------------+---------------------------------------------+
|``CLOB``         |``LONGTEXT``                    |Will be read back as ``LONGVARCHAR``         |
+-----------------+--------------------------------+---------------------------------------------+
|``DATALINK``     |``MEDIUMBLOB``                  |Will be read back as ``LONGVARBINARY``       |
+-----------------+--------------------------------+---------------------------------------------+
|``DATE``         |``DATE``                        |                                             |
+-----------------+--------------------------------+---------------------------------------------+
|``DECIMAL``      |``DECIMAL``                     |                                             |
+-----------------+--------------------------------+---------------------------------------------+
|``DISTINCT``     |``LONGBLOB``                    |Will be read back as ``LONGVARBINARY``       |
+-----------------+--------------------------------+---------------------------------------------+
|``DOUBLE``       |``DOUBLE``                      |                                             |
+-----------------+--------------------------------+---------------------------------------------+
|``FLOAT``        |``DOUBLE``                      |Will be read back as ``DOUBLE``              |
+-----------------+--------------------------------+---------------------------------------------+
|``INTEGER``      |``INTEGER``                     |                                             |
+-----------------+--------------------------------+---------------------------------------------+
|``JAVA_OBJECT``  |``LONGBLOB``                    |Will be read back as ``LONGVARBINARY``       |
+-----------------+--------------------------------+---------------------------------------------+
|``LONGVARBINARY``|``MEDIUMBLOB``                  |                                             |
+-----------------+--------------------------------+---------------------------------------------+
|``LONGVARCHAR``  |``MEDIUMTEXT``                  |                                             |
+-----------------+--------------------------------+---------------------------------------------+
|``NULL``         |``MEDIUMTEXT``                  |Will be read back as ``LONGVARBINARY``       |
+-----------------+--------------------------------+---------------------------------------------+
|``NUMERIC``      |``DECIMAL``                     |Will be read back as ``DECIMAL``             |
+-----------------+--------------------------------+---------------------------------------------+
|``OTHER``        |``LONGBLOB``                    |Will be read back as ``LONGVARBINARY``       |
+-----------------+--------------------------------+---------------------------------------------+
|``REAL``         |``FLOAT``                       |MySQL has a ``REAL`` datatype that is by     |
|                 |                                |default an alias for ``DOUBLE``, though it   |
|                 |                                |might be mapped to ``FLOAT`` via server      |
|                 |                                |configuration. Therefore, DdlUtils explicitly|
|                 |                                |uses ``FLOAT``. Will be read back as         |
|                 |                                |``FLOAT``                                    |
+-----------------+--------------------------------+---------------------------------------------+
|``REF``          |``MEDIUMBLOB``                  |Will be read back as ``LONGVARBINARY``       |
+-----------------+--------------------------------+---------------------------------------------+
|``SMALLINT``     |``SMALLINT``                    |                                             |
+-----------------+--------------------------------+---------------------------------------------+
|``STRUCT``       |``LONGBLOB``                    |Will be read back as ``LONGVARBINARY``       |
+-----------------+--------------------------------+---------------------------------------------+
|``TIME``         |``TIME``                        |                                             |
+-----------------+--------------------------------+---------------------------------------------+
|``TIMESTAMP``    |``DATETIME``                    |``TIMESTAMP`` is not a stable MySQL datatype |
|                 |                                |yet, and it does not support a higher        |
|                 |                                |precision than ``DATETIME`` (year - seconds) |
|                 |                                |as of MySQL 5. DdlUtils thus maps the JDBC   |
|                 |                                |type to ``DATETIME`` instead.                |
+-----------------+--------------------------------+---------------------------------------------+
|``TINYINT``      |``SMALLINT``                    |In MySQL, ``TINYINT`` only has a range of    |
|                 |                                |-128 to +127. Thus DdlUtils uses ``SMALLINT``|
|                 |                                |instead. Will be read back as ``SMALLINT``   |
+-----------------+--------------------------------+---------------------------------------------+
|``VARBINARY``    |``VARBINARY``                   |                                             |
+-----------------+--------------------------------+---------------------------------------------+
|``VARCHAR``      |``VARCHAR``                     |                                             |
+-----------------+--------------------------------+---------------------------------------------+