root/trunk/data/migrations/001_m1.php

<?php
class Migration001 extends sfMigration 
{

  // Adding budget column for jobs table
  public function up() 
  {
    $this->executeSQL("ALTER TABLE jobs ADD COLUMN `budget` VARCHAR(255)");
  }

  // Dropping budget column for jobs table
  public function down() 
  {
    $this->executeSQL("ALTER TABLE jobs DROP COLUMN `budget`");
  }

}