从mysql列sum创建动态表行

I have a little problem here..

I have a code to create an array for a table like this:

$sql = "
    SELECT t.jumBarang,t.hargaJual,b.namaBarang 
    FROM barang AS b, detail_jual AS t
    WHERE t.nomorStruk = '$_POST[idTransaksi2]' AND t.barcode=b.barcode
";
$hasil = mysql_query($sql);

Let's say from the query above it returns 3 rows, so if I want to create that row count as my tr (3 tr) I'll use this code..

while ($x = mysql_fetch_array($hasil)) { #create <tr>   }

so the result become...

<tr></tr>
<tr></tr>
<tr></tr>

But the problem is, how if I want to create a row as my mysql column sum result...

let's say..

ID | Quantity | key
-------------------
1  | 2        | 1
2  | 3        | 1
-------------------

now how to create an array <tr>by using sum(quantity) result (2+3=5 , 5rows)

<tr></tr>
<tr></tr>
<tr></tr>
<tr></tr>
<tr></tr>

Issue another query to calculate the sum:

SELECT sum(*)
FROM barang AS b, detail_jual AS t
WHERE t.nomorStruk = '$_POST[idTransaksi2]' AND t.barcode=b.barcode