public function has_tariffs($parents_id, $column_name1, $comparison1, $value1, $delimiter = '', $column_name2 = '', $comparison2 = '', $value2 = '')
 {
     $database = $_SESSION['database'];
     $employees_roles_listing = '';
     if (tep_not_null($parents_id)) {
         $employees_roles_query = $database->query("select employees_roles_id from " . TABLE_EMPLOYEES_ROLES . " where roles_id in (" . $parents_id . ")");
         while ($employees_roles_result = $database->fetch_array($employees_roles_query)) {
             if (tep_not_null($employees_roles_listing)) {
                 $employees_roles_listing .= ',';
             }
             $employees_roles_listing .= '' . $employees_roles_result['employees_roles_id'];
         }
     } else {
         $employees_roles_listing = $this->id;
     }
     $tariff = new tariff();
     return $tariff->get_tariffs($employees_roles_listing, $column_name1, $comparison1, $value1, $delimiter, $column_name2, $comparison2, $value2);
 }