public function delete($group_provider_id, $precondition_id)
 {
     $dao = new EngineBlock_Model_DbTable_GroupProviderPrecondition();
     if (strlen(trim($group_provider_id)) > 0 && strlen(trim($precondition_id)) > 0) {
         return $dao->delete("group_provider_id='{$group_provider_id}' AND precondition_id='{$precondition_id}'");
     } else {
         return false;
     }
 }