Php 登录页面未根据用户级别正确重定向到用户

我有代码，它给出了错误：

Notice: Undefined index: user_level in C:\xampp\htdocs\user personal\components\login-process.php on line 30

Notice: Undefined variable: user_level in C:\xampp\htdocs\user personal\components\login-process.php on line 31

Notice: Undefined variable: user_level in C:\xampp\htdocs\user personal\components\login-process.php on line 37

用户级别在我的数据库中，我似乎不知道该怎么做

代码如下：

<?php
    session_start();
    if(isset($_REQUEST['login_button'])||$_REQUEST['auto']==1){
        require '../_database/database.php';
        $errmsg_arr = array();
        $errflag = false;
        $username=  mysqli_real_escape_string($database,$_REQUEST['username']);
        $password=  mysqli_real_escape_string($database,$_REQUEST['password']);
        if($username == '') {
            $errmsg_arr[] = 'Username missing';
            $errflag = true;
        }
        if($password == '') {
            $errmsg_arr[] = 'Password missing';
            $errflag = true;
        }
        if($errflag) {
            $_SESSION['ERRMSG_ARR'] = $errmsg_arr;
            session_write_close();
            header("location: authentication-check.php");
            exit();
        }
        $sql="SELECT user_username,user_password FROM user WHERE user_username='$username'AND user_password='$password'";
        $result=  mysqli_query($database,$sql) or die(mysqli_errno());
        $trws= mysqli_num_rows($result);
        if($trws==1){
            $rws=  mysqli_fetch_array($result);
            $_SESSION['user_username']=$rws['user_username'];
            $_SESSION['user_password']=$rws['user_password'];
              $_SESSION['user_level'] =$rws['user_level'];
            if($user_level == "1"){
            //to admin home
           header("Location: ../files/A-HOMEPAGE.php");
            exit();
            }
            //to user home
            elseif($user_level == "2"){
            header("Location: ../user/A-HOMEPAGE.php");
            exit();
            }    
        }
        else {
            $errmsg_arr[] = 'user name and password not found';
            $errflag = true;
            if($errflag) {
                $_SESSION['ERRMSG_ARR'] = $errmsg_arr;
                session_write_close();
                header("location: ../components/authentication-check.php");
                exit();
            }
        }
    }
?>

正如错误所说，

$user\u level

变量尚未定义。在定义if语句之前，您正在检查if语句中

$user\u level

的值。也许你想设置

$user\u level=$\u SESSION['user\u level']

？我已经尝试了你刚才给出的解决方案，错误消失了，但是它显示了一个带有登录页面地址的空白页面。因此重定向到给定页面不起作用。我应该在这里做什么！！？谢谢