$bul = mysqli_query($conn, "select * from users where user_name='$username' && password='$password'");
        $say = mysqli_num_rows($bul);

        if ($say > 0) {

            $goster = mysqli_fetch_array($bul);

            $_SESSION["oturum"] = true;
            $_SESSION["username"] = $username;
            $_SESSION["password"] = $password;
            $_SESSION["reg_group"] = $goster['reg_group'];
            header("Location:index.php");
        }