/**
  * Get foreign fields needed to process criterias
  *
  * @return an array of needed fields
  **/
 function getFKFieldsForQuery()
 {
     $rule = new RuleOcs();
     $fields = array();
     foreach ($rule->getCriterias() as $criteria) {
         //If the field name is not null AND a table name is provided
         if ((!isset($criteria['virtual']) || !$criteria['virtual']) && $criteria['linkfield'] != '') {
             $fields[] = $criteria['table'] . "." . $criteria['linkfield'];
         }
     }
     return $fields;
 }