MySQLi准備語句查詢問題

Question

我對MySQLi准備的語句比較陌生，並且遇到錯誤。 采取以下代碼：

$user = 'admin';
$pass = 'admin';

if ($stmt = $mysqli->query("SELECT * FROM members WHERE username='$user' AND     password='$pass'"))
{
echo $stmt->num_rows;
}

它將顯示為“ 1”。

下一段代碼雖然返回“ 0”：

$user = 'admin';
$pass = 'admin';

if ($stmt = $mysqli->prepare("SELECT * FROM members WHERE username=? AND password=?"))
{
$stmt->bind_param("ss", $user, $pass);
$stmt->execute();
echo $stmt->num_rows;
}

有什么想法嗎？

Answer 1

您需要在獲取行數之前調用store_result()

$user = 'admin';
$pass = 'admin';


if ($stmt = $mysqli->prepare("SELECT * FROM members WHERE username=? AND password=?")) { $stmt->bind_param("ss", $user, $pass); $stmt->execute(); $stmt->store_result(); // add this line echo $stmt->num_rows; }