yii2 dropdownlist

 Controller

public function actionIndex(){
        
        $data = Yii::$app->request->post();
        $hospcode = isset($data['hospcode']) ? $data['hospcode'] : 'null';
        $sex = isset($data['sex']) ? $data['sex'] : '1,2';
        $date1 =isset($data['date1'])  ? $data['date1'] : '';
        $date2 =isset($data['date2'])  ? $data['date2'] : '';
     
     
        $sql = "SELECT p.CID,p.`NAME`,p.LNAME,p.SEX,p.BIRTH
,TIMESTAMPDIFF(YEAR,p.BIRTH,CURDATE()) as AGE_Y
,TIMESTAMPDIFF(MONTH,p.BIRTH,CURDATE()) MOD 12 as AGE_M
,p.TYPEAREA,p.NATION,p.DISCHARGE from person p

WHERE p.DISCHARGE = 9 AND p.TYPEAREA in (1,3,5)
AND p.HOSPCODE = '$hospcode'
AND p.SEX in ($sex)";
        if(!empty($date1) && !empty($date2)){
            $sql.= " AND (p.BIRTH between '$date1' AND '$date2')";
        }
        $sql.= " ORDER BY p.BIRTH DESC,AGE_Y ASC,AGE_M ASC";
     
         $rawData = \Yii::$app->db->createCommand($sql)->queryAll();
        $person = new \yii\data\ArrayDataProvider([
            //'key' => 'hoscode',
            'allModels' => $rawData,
            'pagination' => FALSE,
        ]);


        return $this->render('index',[
            'hospcode'=>$hospcode,
            'person'=>$person,
            'sql'=>$sql,
            'sex'=>$sex,
            'date1'=>$date1,
            'date2'=>$date2,
         
        ]);
 
    }