Versuchen Sie Folgendes:
$test = "SELECT c_id, MAX(Bought) AS MaxBought FROM (SELECT c_id, SUM(n_sell) AS Bought FROM sell GROUP BY c_id) AS tmp HAVING MAX(Bought) = tmp.Bought";
$resut = mysql_query($test) or die(mysql_error());
while($t = mysql_fetch_array($resut)){
echo "Number of sold: ". $t['MaxBought'] ." to". $t['c_id'] .":id of customer";
echo "<br />";
}
Hier ist nur die SQL-Abfrage zum besseren Verständnis:
SELECT c_id, MAX(Bought) AS MaxBought
FROM (SELECT c_id, SUM(n_sell) AS Bought
FROM sell
GROUP BY c_id) AS tmp
HAVING MAX(Bought) = tmp.Bought