Search report sql login in php

$dat=$post['rep_cal'];
    $day=substr($dat,0,2);
    $month=substr($dat,3,2);
    $year=substr($dat,6,4);
    $moddate=$year."-".$month."-".$day;
    $TotalDispRec =0;
    $AppID;
   
    $patient=$post['pat_id'];
    $doctor=$post['doc_id'];
    $status=$post['pay_status'];
    $payment=$post['pay_id'];
   
    if($dat!='')
    {
    $QueryPart.= " AND bil_date = '".$moddate."'";
    }   
    if($patient !='')
    {
    $QueryPart.= " AND pat_id = ".$post['pat_id'];
    }
   
    if($doctor !='')
    {
    $QueryPart.= " AND d.doctor_id = ".$post['doc_id'];
    }
    if($status !='')
    {
    $QueryPart.= " AND b.pay_status = '".$post['pay_status']."'";
    }
   
    if($payment!='')
    {
    $QueryPart.= " AND b.bill_pay_mode = ".$post['pay_id'];
    }
   
    if($QueryPart != ''){
            $QueryPart = substr($QueryPart,4,strlen($QueryPart));
            $QueryPart="where ".$QueryPart;
    }
   
       
     $sql="SELECT * from `bill_master` b INNER JOIN appointment_master a
        ON b.`app_id`=a.`appoint_id`  INNER JOIN `doctor_master` d
        ON a.`doctor_id`=d.`doctor_id` INNER JOIN patient_registration p
        ON a.`pat_rec_id`=p.`pat_rec_id`   ".$QueryPart;
    //echo $sql;
        $AppointArr = $DBFn->SimpleRunQuery($sql, $RowCnt);
         $TotalDispRec = count($AppointArr);