How To Access Data In From Database?

i hav a table "student"(id,rollno,name,class,division,subject1,subject2,subject3,subject4,subject5).

Here in this fields i enter the respective datas and in the (subject1,subject2…) i enter the respective subject from the dropdownlist with the help of another table "mastersubject"

And i do also hav another table "result"(id,rollno,subject1,subject2,subject3,subject4,subject5), here in this subject fields i enter the respective marks. I have made the "rollno" field foriegn key.

Now i hav a form in the yii in which ,when i select the "rollno" i need to get the marks of respective students.

so i need to write the

public function actionResult()

{


	 //renders the view file 'protected/views/site/index.php'


	//using the default layout 'protected/views/layouts/main.php'


	$model=new student;








	if(isset($_POST['student']))


	{


		$model->attributes=$_POST['student'];


		$res=0;


		$roll = $model->rollno;


		$class = $model->class;


		$division= $model->division;


	


		$result =result::model()->findAllByAttributes(array('rollno'=>$roll)   





       foreach( $result as $dev)


		{


			echo $dev['rollno'];


			echo "subject1:".$dev['subject1'];


			


			





	}


	


	$this->render('result',array(

‘model’=>$model,

));

}

can anyone help with this,i really new to yii. so please do help me. Thanks in advance.