$q = new Doctrine_RawSql();
    $q->select('{f.*},{ft.*}')
      ->from('Forum f')
      ->leftJoin('Status s ON s.libelle LIKE "Published"')
      ->leftJoin('Forum_topic ft ON f.id = ft.forum_id AND ft.status_id = s.id')
      ;

    $q->addComponent('f', 'Forum f');
    $q->addComponent('ft', 'ForumTopic');