tolong bantuannya

<?php
require 'koneksi.php';
if(isset($_POST['submit'])) {
$custom = $_POST['custom'];
$pass = md5($_POST['pass']);
$query = "SELECT * FROM user WHERE custom='$custom' AND pass='$pass'";
$login    = mysqli_query($connect, $query);
$result   = mysqli_num_rows($login);
    if($result > 0) {
        $user = mysqli_fetch_assoc($login);
        session_start();
        $_SESSION['id'] = $user['id'];
        $_SESSION['url'] = $user['url'];
        $_SESSION['custom'] = $user['custom'];
        $_SESSION['visitor'] = $user['visitor'];
    }