PDO 案例存在不适用于绑定参数

Question

我正在检查 table?

中是否存在用户名和密码组合

我正在使用绑定参数在 PDO 中执行此操作。执行页面时显示错误：currently unable to handle this request.

这是我的代码：

    $stmtus = $conn->prepare("Select
                case
                when exists (
                Select 1 from School_Profile 
                where aes_decrypt(SchoolEmail, 'SALT') = :Username  and password = :Password
                ) then 'Admin'
                when exists (
                Select 1 from NonAdminUsers 
                where aes_decrypt(Nuser, 'SALT') = :Username and Npassword = :Password
                ) then 'Non Admin'
                else 'Unknown'
                end result");
 $stmtus->bindParam(':Username', $username);
 $stmtus->bindParam(':Password', $password);
 $username = htmlspecialchars($_POST['username'], ENT_QUOTES, 'UTF-8');
 $password = htmlspecialchars($_POST['password'], ENT_QUOTES, 'UTF-8');
 $stmtus -> execute();

我的错误日志显示：

PHP Fatal error: Uncaught Error: Call to a member function prepare() on null in

Answer 1

据我所知，您不能多次重复使用命名参数，这很可能是您出错的根源。因此，为了快速解决问题，请不要两次或多次使用相同的参数：

$stmtus = $conn->prepare("SELECT
    CASE WHEN EXISTS (
             SELECT 1 FROM School_Profile
             WHERE AES_DECRYPT(SchoolEmail, 'SALT') = :user1 AND password = :pass1)
         THEN 'Admin'
         WHEN EXISTS (
             SELECT 1 FROM NonAdminUsers
             WHERE AES_DECRYPT(Nuser, 'SALT') = :user2 AND Npassword = :pass2)
         THEN 'Non Admin'
         ELSE 'Unknown'
         END result");

$stmtus->bindParam(':user1', $username);
$stmtus->bindParam(':pass1', $password);
$stmtus->bindParam(':user2', $username);
$stmtus->bindParam(':pass2', $password);
$username = htmlspecialchars($_POST['username'], ENT_QUOTES, 'UTF-8');
$password = htmlspecialchars($_POST['password'], ENT_QUOTES, 'UTF-8');
$stmtus->execute();

PDO 案例存在不适用于绑定参数

PDO case exist not working with bind parameters

mysql

pdo

case

exists