create on submit achievement

public function actionCreate()
    {
        $model=new Achievement;
        $modelTestSchedule = new TestSchedule;
        $modelTeachingMap = new TeachingMap;
        $modelTeacher = Teachers::getTeacherList();

        if(isset($_POST['Achievement']))
        {
                ...
                foreach($data['student_id'] as $key=>$value)
                {
                        // $sql = {your sql, for example:}
                        $sql .= "INSERT INTO achievement(student_id,result_value) VALUES('{$value}','{$data['result'][$key]}');";
                    ++$i;
                }

                /* Transasction begin */

            $connection = Yii::app()->db;
            $transaction= $connection->beginTransaction();
            try
            {
                $connection->createCommand($sql)->execute();
            }
            catch(Exception $e)
            {
               $transaction->rollBack();
               throw new CHttpException(400,$e->getMessage());
            }
        }

        $this->render('create',array(
            'model'=>$model,
            'modelTestSchedule'=>$modelTestSchedule,
            'modelTeachingMap'=>$modelTeachingMap,
            'modelTeacher'=>$modelTeacher,
        ));
    }