รบกวนขอโค้ดหรือแนะนำการบวก ลบ ข้อมูลต่าง table ทีค่ะ

$strSQL = "INSERT INTO pj_list_expose";

        $eNo = $_POST["expose_No"];
        $ec = $_POST["expose_code"];
        $ed = $_POST["expose_id"];
        $et = $_POST["expose_type"];
        $en = $_POST["expose_name"];
        $es = $_POST["expose_size"];
        $ep = $_POST["expose_price"];
        $em = $_POST["expose_price"] * $_POST["expose_remain"];
        $eb = $_POST["expose_remain"];
        $ey = $_POST["expose_pay"]; 

  $strSQL = "SELECT `product_remain` FROM `pj_list_product` WHERE `product_id` = '$ed'";
  $objQuery = mysql_query($strSQL);
  $tem;
  while($objResult = mysql_fetch_array($objQuery)){
      $tem= $objResult['product_remain'];
    
  }
  $ey = $tem-$eb;


$strSQL="INSERT INTO pj_list_expose (expose_code ,expose_date,expose_time,expose_id,expose_type, expose_name, 
    expose_size, expose_price,expose_num, expose_remain, expose_pay ) VALUES ('$ec','".date("Y-m-d")."','".date("H:i:s")."','$ed','$et','$en','$es','$ep','$em','$eb','$ey') ";
$objQuery = mysql_query($strSQL);

  $strSQL = "UPDATE `pj_list_product` SET product_remain = $ey WHERE `product_id` = '$ed'";
 $objQuery = mysql_query($strSQL);