如何从mysql_fetch_array添加值？

Here is my code but it displays two different sum of values. I have total with per row and it has 2 value 100 and 200 . it displays 100 and 200 seperately. But i want the sum of 100 and 200 . sum= 300 how could i do it?

$result2 = mysql_query("select * from price  where dom='$cat'",$db);
while ($myrow2 = mysql_fetch_array($result2))
{
    echo $myrow2["totalwithper"];
}

here is my table structure

CREATE TABLE `price` (
  `id` int(5) NOT NULL AUTO_INCREMENT,
  `dom` varchar(255) COLLATE utf8_bin NOT NULL,
  `etiket` varchar(255) COLLATE utf8_bin NOT NULL,
  `pricestandart` int(5) NOT NULL,
  `number` int(5) NOT NULL,
  `totalunper` int(5) NOT NULL,
  `discount` int(5) NOT NULL,
  `totalwithper` int(5) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_bin AUTO_INCREMENT=20 ;

--
-- Dumping data for table `price`
--

INSERT INTO `price` (`id`, `dom`, `etiket`, `pricestandart`, `number`, `totalunper`, `discount`, `totalwithper`) VALUES
(18, 'Alten Group', 'flayer', 100, 1, 100, 10, 90),
(19, 'Alten Group', 'logo', 100, 2, 200, 15, 170);

Try this:

  $result2 = mysql_query ("select sum(totalwithper) from price  where dom='$cat'",$db);
  $myrow2= mysql_fetch_array($result2);
  do{
     echo $myrow2["totalwithper"];
    }
    while($myrow2=mysql_fetch_array($result2));

a small rewrite to your code :

 $result2 = mysql_query ("select sum(totalwithper) from price  where dom='$cat'",$db);
 while($myrow2=mysql_fetch_array($result2))
        {
         echo $myrow2["totalwithper"];
        }

sum by loop

 $sum=0;
 $result2 = mysql_query ("select totalwithper from price  where dom='$cat'",$db);
 while($myrow2=mysql_fetch_array($result2))
        {
         $sum=$sum+ $myrow2["totalwithper"];
        }

 echo "sum : $sum";

In $sum you will get the sum.

SELECT Sum(totalwithper) FROM price  WHERE ...

see:

Use

$result2 = mysql_query ("select sum(totalwithper) from price  where dom='$cat'",$db);

I have spent the last couple of days trying to make the array_sum() function work and it would print out every number but wouldn't add them together. But with this code it finally worked for me TY.

 $sum=0;
 $result2 = mysql_query ("select totalwithper from price  where dom='$cat'",$db);
 while($myrow2=mysql_fetch_array($result2))
 {
    $sum=$sum+ $myrow2["totalwithper"];
 }

 echo "sum : $sum";