Mysql查询不显示列的总和

Question

知道为什么这不起作用？当我运行它时，它不会显示任何内容。

$qry = mysql_query(" SELECT SUM(payment_received) AS total FROM Orders ");
   {
 $row = mysql_fetch_assoc($qry);
echo $row['total'];
}

感谢您的帮助。

Answer 1

$result = mysql_query("SELECT SUM(payment_received) AS total FROM Orders") or die(mysql_error());
$row = mysql_fetch_assoc($result);
print_r($row);

Answer 2

使用以下示例

更正您的代码

$qry = mysql_query("SELECT SUM(payment_received) AS total FROM Orders");
while ($row = mysql_fetch_assoc($qry)) {
{
    echo $row["total"];
}