function buildDistinctQueryForVehicleEntityIdMappings(Zend_Db_Select $select, VF_Vehicle $vehicle)
 {
     $subSelect = $this->getReadAdapter()->select();
     foreach ($this->schema()->getLevels() as $current_level) {
         $level = $vehicle->getLevel($current_level);
         if (!$level->getId()) {
             continue;
         }
         $subSelect->where(sprintf("%s = ?", $current_level), $level->getTitle());
     }
     $select = $this->combineSubSelectIfWhereIsNotEmpty($select, $subSelect);
     return $select;
 }