I have a question when implementing a login form using PHP.

For PHP practice, I want to create a login form after simply linking DB, but there was an error, so I'm asking you this question. The database integration was successful by entering the source as below and confirming the message Success.

<?php
    $db_host="localhost";
    $db_user="root";
    $db_password="159874";
    $db_name="loginFunc";
    $connect=mysqli_connect($db_host, $db_user, $db_password, $db_name);

    if(mysqli_connect_errno($connect)) {
        echo "Failed loading database connect :".mysqli_connect_error();
    } } else {
        echo "Success";
    }
?>

In order to simply create a table in MySQL and take over the value from the input form, the following source is added, but the following error occurs:

<?php
    $userId=$_POST['userId'];
    $userPass=$_POST['userPass'];
?>

Notice: Undefined index: userId in /Users/KimMinWoo/Laravel/LoginFunc/login.php on line 2

Notice: Undefined index: userId in /Users/KimMinWoo/Laravel/LoginFunc/login.php on line 3