Mysqli准备声明选择不起作用

Question

这份准备好的声明有什么问题？我似乎无法让这个工作。

$session = mysql_real_escape_string($_GET['s']);

$stmt = $mysqli->prepare("SELECT quantity FROM details WHERE session = ?");
$stmt->bind_param( "s", $session); 
$stmt->execute();
$stmt->bind_result($quantity);

当我echo $quantity;时，结果只显示为0时，它应显示1到10之间的数字。

Answer 1

$stmt = $mysqli->prepare("SELECT quantity FROM details WHERE session = ?");
$stmt->bind_param( "s", $session); 
$stmt->execute();
$stmt->bind_result($quantity);
$stmt->fetch();

echo $quantity