if(startdate='startdate' between startdate(Y-m-(d+'daysleave')->where('status'=='approved')
{
    $_post = 'status'=rejected,
        'applydate=date('Y-m-d'),
        'startdate';
    )
} else {

}

if ($model->load(Yii::$app->request->post()))
{
    //Proses Validasi if no more quota left
    if($model->daysleaveleft(Yii::$app->user->id,date('Y',strtotime($model->startdate)))>0)
    {
        //Validate if startdate< applydate
        if($model->startdate < $model->applydate)
        {
            echo "Cannot proceed";
        }
        else
        {
            $model->save();
            return $this->redirect(['view', 'id' => $model->id]);
        }
    }
    else
    {
        echo"Maximum Quota";
    }
}
else
{
    return $this->render('create', [
        'model' => $model,
    ]);
}

public function DaysLeaveLeft($id,$year) {
    $models = Leave::find()->select(['daysleave'=>'sum(daysleave)'])->where(['status'=>'approved','EmpId' => $id,'year(startdate)'=>$year])->One();
    $Setting = Setting::find()->where(['Var'=>'MaxLeave'])->One();
    return $Setting->Val - $models['daysleave'];
}