如何在PHP中多次汇总mysql值

Question

i like to sum all row values from the $orderfeed_query. But when i echo the $sum, i get just the sum from the last loop.

how can can i add the sum of all following loop on the $sum variable? I dont know how many loops a order have.

$checkorder = mysql_query("SELECT * FROM orders WHERE  `email` = '$email' ") or die(mysql_error());
while ($row = mysql_fetch_assoc($checkorder)) {
    $orderid = $row["orderid"];
    $check_order = $row["check_order"];

    if($check_order[0] == 1){

        $orderfeed_query = mysql_query("SELECT * FROM orderfeed WHERE `orderid` = '$orderid' AND `product` = '1'") or die(mysql_error());
        while ($row = mysql_fetch_assoc($orderfeed_query)) {
            $signaturewiz = $row["signaturewiz"];
            $flurstueckwiz = $row["flurstueckwiz"];
            $uploadwiz = $row["uploadwiz"];
            $exsignaturewiz = $row["exsignaturewiz"];
            $ibanwiz = $row["ibanwiz"];

            $sum = $signaturewiz+$flurstueckwiz+$uploadwiz+$exsignaturewiz+$ibanwiz;

            echo $sum;

        }
    }   

}
}   

Answer 1

This code

$sum = $signaturewiz + $flurstueckwiz + $uploadwiz + $exsignaturewiz + $ibanwiz;

overwrites sum each time. You must add to sum not to overwrite

$sum += $signaturewiz + $flurstueckwiz + $uploadwiz + $exsignaturewiz + $ibanwiz;

And declare $sum = 0; before main loop