Doctrine_manual-1-2-en

Chapter 24: Migrations 328
Omitting the version number argument for the migrate() method means that internally
Doctrine will try and migrate to the latest class version number that it could find in the
directory you passed.
Transactions in Migrations
Internally Doctrine does not wrap migration versions in transactions. It is up to you as the
developer to handle exceptions and transactions in your migration classes. Remember
though, that very few databases support transactional DDL. So on most databases, even if
you wrap the migrations in a transaction, any DDL statements like create, alter, drop,
rename, etc., will take effect anyway.
Implement
Now that we know how to perform migrations lets implement a little script in our Doctrine
test environment named migrate.php.
First we need to create a place for our migration classes to be stored so lets create a
directory named migrations:
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$ mkdir migrations
Now create the migrate.php script in your favorite editor and place the following code
inside:
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// migrate.php
require_once('bootstrap.php');
$migration = new Doctrine_Migration('migrations');
$migration->migrate();
Writing Migration Classes
Migration classes consist of a simple class that extends from Doctrine_Migration. You can
define a up() and down() method that is meant for doing and undoing changes to a database
for that migration version.
The name of the class can be whatever you want, but the name of the file which contains
the class must have a prefix containing a number that is used for loading the migrations in
the correct order.
Below are a few examples of some migration classes you can use to build your database
starting from version 1.
For the first version lets create a new table named migration_test:
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// migrations/1_add_table.php
class AddTable extends Doctrine_Migration_Base
{
public function up()
{
$this->createTable('migration_test', array('field1' =>
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