login hex

function login() {
        $username = $_POST['username'];
        $password = bcrypt($_POST['password']);

        if(isset($_POST['submit'])) {
            if(!empty($username) && !empty($password)) {
                $query = mysqli_query("SELECT username, password FROM users WHERE username = '$username' AND password = '$password'");

                if(mysqli_num_rows($query) > 0) {
                    $_SESSION['user'] = true;
                    $_SESSION['user'] = $query['id'];
                }
            }
        }
    }