多角色用户登录和会话

Question

我在PHP MySQL中使用多角色用户登录时遇到问题，我在没有错误处理的情况下尝试了代码，以查看它是否有效，但是无效；任何提示将不胜感激谢谢您

session_start();

if( isset($_POST['submit'])){   

    include 'db.php';

    $username = mysqli_real_escape_string($conn,$_POST['username']);
    $password = mysqli_real_escape_string($conn,$_POST['password']);

    $sql = "SELECT * FROM utilisateur WHERE username = '$username'";    
    $result = mysqli_query($conn,$sql);
    if ($row = mysqli_fetch_assoc($result)){

        $SESSION['Id'] = $row['Id'];    
        $SESSION['login'] = $row['login'];
        $SESSION['type'] = $row['type'];
        if( $SESSION['type'] == "admin" ){
        header('Location: admin.html');}
        else if( $SESSION['type'] == "Cardio" ){
        header('Location: Cardio.html');}
    }
}