public function updateStudentTuitions($classId, $tuitions)
 {
     try {
         $tId = session('instId');
         $sts = explode('|', $tuitions);
         $class = new \Home\Model\ClassModel();
         $class->startTrans();
         for ($i = 0; $i < count($sts); $i++) {
             $st = explode(':', $sts[$i]);
             $class->updateStudentTuitionForClass($tId, (int) $classId, (int) $st[0], (int) $st[1] * 100);
             $class->updateStudentTuitionForClassDetailAndStudentRela($tId, (int) $classId, (int) $st[0], (int) $st[1] * 100);
         }
         $class->commit();
         $data = "true";
     } catch (Exception $e) {
         $class->rollback();
         $data = "false";
     }
     $this->ajaxReturn($data);
 }