MySQLdb: a Python interface for MySQL: Introduction

1. Introduction

This module should be mostly compatible with an older interface written by Joe Skinner and others. However, the older version is a) not thread-friendly (database operations could cause all other threads to block), b) written for MySQL 3.21 (does not compile against newer versions without patches), c) apparently not actively maintained. MySQLdb is a completely new module, distributed free of charge under the GNU Public License.

1.1 Platforms

Linux/UNIX

This module is developed on RedHat Linux (currently 7.1) for Intel. It should build without much trouble on most platforms by using the setup.py script. Supposedly it builds on MacOS X. Be aware that you need the Distutils package which comes with Python 2.0. If you don't have it (i.e. you have Python 1.5.2), you can find it over at www.python.org.

Windows (3.11, 95, 98, NT, 2000, CE, BSOD, XYZ, etc.)

Windows is not a supported platform. However, the setup.py script reportedly gets the job done. There is probably a link on the web page for getting a precompiled Windows installer from someone or other. Be aware that this is a user-contributed package; the author cannot help you with compiling and running under Windows.

1.2 Python

MySQLdb requires Python 1.5.2 or newer. Earlier versions will not work, because support for C long long is required by MySQL. If you have an earlier version of Python, upgrade to 1.5.2 or beyond. Current development is done with Python 2.1, but Python 1.5.2 will be supported for the forseeable future.

1.3 MySQL

MySQL-3.22

Only versions 3.22.32 and up are guaranteed to work. Some older versions may work; if you have an older version you should seriously consider upgrading to get the bug fixes and particularly the security updates.

MySQL-3.22 seems to have a problem trying to insert TIME values with fractional seconds. Values like 12:56:13.00 are returned as 344:13:00, apparently interpreting the original input as 12 days, 56 hours, 13 minutes, 0 seconds. (12 days and 56 hours is 344 hours.) To avoid this problem, use the DateTimeDelta type.

MySQL-3.23

MySQL-3.23 is now stable (3.23.37 as of this writing). MySQLdb supports transactions if the server supports them. Even then, this does not guarantee that transactions will work. For that, you must use a transaction-safe table (TST). Current TSTs are BDB and InnoDB. GEMINI tables are slated for MySQL-4.0. Note that MySQL generally operates in AUTOCOMMIT mode by default, and MySQLdb assumes that AUTOCOMMIT is on by default. To change this, use the SET AUTOCOMMIT=0 SQL statement.

1.4 DateTime

If you have the mx.DateTime package installed (recommended), MySQLdb will use it for date-related objects. Otherwise, these will be returned to Python as strings. You can also modify the type conversion dictionary to return these as other object classes, if you prefer.

1.5 MySQLmodule

MySQLmodule, the older MySQL interface by Joe Skinner and others, is also a split C/Python interface. MySQL, the C portion, has an interface similar to perl's DBI internally. In addition, there is Python portion, Mysqldb, which provides a DB API v1.0 interface, written by James Henstridge. MySQLdb-0.2.2 and up include CompatMysqldb, which is an adaptation of Mysqldb to _mysql. It should be considered experimental.

In contrast, MySQLdb's C portion, _mysql, is designed to mimic the MySQL C API in an object-oriented way; you should not expect to move from MySQL to _mysql without a fair amount of work. MySQLdb provides a DB API v2.0 interface, which has some changes from the v1.0 interface. Things to watch out for in particular:

Mysqldb to MySQLdb changes
Operation	Mysqldb	MySQLdb
Connecting	`db = Mysqldb.Mysqldb("db@host user pass")`	`db = MySQLdb.connect(db='db', host='host', user='user', passwd='pass')`
Implicit cursor	`db.execute(SQL)`	implicit cursors dropped from DB API v2.0; always use `c = db.cursor()`
Fetch row as dictionary	`c.fetchDict()`,keys are "table.column"	not standard; alternate cursor class `DictCursor`provides a dictionary interface,keys are "column" or "table.column" if there are two columnswith the same name; use SQL `AS` to rename fields.
Transactions	`db.commit()` and `db.rollback()`both exist and silently do nothing (danger!)	`db.commit()` and `db.rollback()` work if the MySQLserver can perform transactions; otherwise `db.rollback()`always fails