<?php
session_start();
$_SESSION['message'] = '';
$mysqli = new mysqli('localhost','root','','users');
$alert = false;
if ($_SERVER['REQUEST_METHOD'] == 'POST'){
        $username = $mysqli->real_escape_string($_POST['username']);
        $password = md5($_POST['password']);
        $sql = "SELECT * FROM `users`.`users` WHERE username=`$username` and password=`$password`";
        if ($mysqli->query($sql) === true){
            $_SESSION['message'] = 'Login!';
            header('Location: http://localhost/index.html');
            exit();
        }
        else{
            $_SESSION['message'] = "Username or password incorrect!";
            $alert = true;
    }
}
else{
    $_SESSION['message'] = "Something went wrong!";
    $alert = true;
}
?>