Gan n Sis, mau tanya kalau error ini kenapa ya. Maklum udah lama ga ngoding lagi 
mysql_num_rows() expects parameter 1 to be resource, boolean given in C:\xampp\htdocs\login\login.php on line 10

<?php
session_start();
include "config/koneksi.php";

@$username = $_POST['user'];
@$password = $_POST['pass'];

    if(isset($_POST['login'])){
      $sql = mysql_query("SELECT * FROM tb_user WHERE user ='$username' AND pass ='$password'");
      $cek = mysql_num_rows($sql);
        if ($cek > 0) {
          $_SESSION['user'] = $_POST['user'];
          echo "[removed]alert ('Selamat Datang $username');document.location.href='home.php'; [removed]";
        }
        else {
          echo "[removed]alert ('Maaf username atau password Anda salah') [removed]";  
        }
    }
?>  

mohon bantuannya