O Guia Definitivo do Yii 1.1

class m101129_185401_create_news_table extends CDbMigration
{
public function up()
{
$this->createTable('tbl_news', array(
'id' => 'pk',
'title' => 'string NOT NULL',
'content' => 'text',
));
}
}
public function down()
{
$this->dropTable('tbl_news');
}
The base class CDbMigration provides a set of methods for manipulating data and
schema of a database. For example, CDbMigration::createTable will create a database
table, while CDbMigration::insert will insert a row of data. These methods all use the
database connection returned by CDbMigration::getDbConnection(), which by default
returns Yii::app()->db.
Info: You may notice that the database methods provided by CDbMigration are very
similar to those in CDbCommand. Indeed they are nearly the same except that
CDbMigration methods will measure the time used by their methods and print some
messages about the method parameters.
Applying Migrations
To apply all available new migrations (i.e., make the local database up-to-date), run the
following command:
yiic migrate
The command will show the list of all new migrations. If you confirm to apply the
migrations, it will run theup() method in every new migration class, one after another, in the
order of the timestamp value in the class name.
After applying a migration, the migration tool will keep a record in a database table named
tbl_migration. This allows the tool to identify which migrations have been applied and
which are not. If the tbl_migrationtable does not exist, the tool will automatically create it in
the database specified by the db application component.