/**
  * Returns trainers in training session
  */
 public static function getTrainers($training_id)
 {
     $tableObj = new TrainingToTrainer();
     $select = $tableObj->select()->from(array('ttt' => $tableObj->_name), array('id', 'trainer_id', 'duration_days'))->setIntegrityCheck(false)->join(array('p' => 'person'), "p.id = ttt.trainer_id", array('first_name', 'middle_name', 'last_name'))->where("ttt.training_id = {$training_id}")->order("last_name");
     return $tableObj->fetchAll($select);
 }