อยากให้ตัวแปรที่คำนวณแล้วได้ค่าผลลัพธ์ ไปเก็บในฐานข้อมูล (มีโค๊ด มีรูป ฮ่ะ)ช่วยหน่อยครับ

<? 
$cmd_s = "select * from sale where cus_id = '$c_id' and sale_status = 'presale' ";
$result_s = mysql_query($cmd_s,$link);
while($row_s=mysql_fetch_array($result_s))
{
?>
       <tr bgcolor="#B2DFFF">
          <td align="center" bgcolor="#FFFFFF"><span class="style27">
<?
 if($row_s[sale_due] == $fullday) {echo"<b><font size='2' color = 'blue'>$row_s[sale_id]</font></b>"; }else {echo"<font size='2'>$row_s[sale_id]";}
?>
	</span> </td>
          <td align="deafult" bgcolor="#FFFFFF"><span class="style27">
<? 		
$n=0;
$total_cost=0;   						
$cmd_st= "select * from saletemp where sale_id = '$row_s[sale_id]'";
$result_st = mysql_query($cmd_st,$link);
while($row_st=mysql_fetch_array($result_st))
{
$cmd_pros = "select * from productstock  where pros_id = '$row_st[pros_id]'";
$result_pros = mysql_query($cmd_pros,$link); 
$row_pros = mysql_fetch_array($result_pros);
$cmd_num = "select * from saletemp  where pro_auto = '$row_pros[pro_auto]' and sale_id='$row_s[sale_id]' "; 
$result_num = mysql_query($cmd_num,$link); 
$num = mysql_num_rows($result_num);
$cmd_pro = "select * from product  where pro_auto = '$row_pros[pro_auto]'"; 
$result_pro = mysql_query($cmd_pro,$link); 
$row_pro = mysql_fetch_array($result_pro);
if($test != $row_st[pro_auto])
{
$n++;
$cost=$row_pro[pro_pricesale]*$num;
$total_cost+=$cost ; 
						
if($row_s[sale_due] == $fullday) 
{
echo"<b><font size='2' color = 'blue'>$n : $row_pro[pro_name] <font size='1' color = 'green'>[ $num ชิ้น $cost bath ]</font><BR>";
}
else
{
echo"<font size='2'>&nbsp;&nbsp;$n : $row_pro[pro_name] <font size='1' color = 'green'>[ $num ชิ้น $cost bath ]</font><BR>";
}
}
$test = $row_st[pro_auto];	
						
}
?>
	span> </td>
          <td align="center" bgcolor="#FFFFFF"><span class="style27">
<?
 if($row_s[sale_due] == $fullday) {echo"<b><font size='2' color = 'blue'>$row_s[sale_cost]</font></b>"; }else {echo"<font size='2'>$row_s[sale_cost]";}
?>