return Doctrine_Query::create()
            ->select('v.*')
            ->from('Video v')                   
            ->where("v.community_id='$community_id' AND v.user_id='$user_id' AND v.published='$published'")
            ->orderBy('v.id DESC')
            ->limit(10)
            ->execute(); 

上面这段其实是limit 0,10,该如何写limit 10,10？