ini memakai ajax..

<?php
if(isset($_GET['act']) )
{

    $act=$_GET['act'];

    if($act=='check')
    {

            foreach($_POST as $n=>$v)$$n=$v;
        require("config.php");
session_start();
        error_reporting(1);
        //  print_r($_POST);
        $username = $_POST['username'];
        $password = $_POST['pass'];
        $type=0;
        $a=array();
        $sql="";

        $query = "SELECT * FROM admin WHERE username='$username' AND pass='$password'";
        $result = mysql_query($query,$con);// or die(mysql_error());
        $num_row = mysql_num_rows($result);
        if($num_row){
            $type='admin';
            $url="admin/index.php";
        }
        $sql.="<br/>$query";

        $query = "SELECT * FROM alumni WHERE username='$username' AND pass='$password'";
        $result = mysql_query($query,$con);// or die(mysqli_error());
        $num_row = mysql_num_rows($result);
        $sql.="<br/>$query";
        if($num_row&&$type==0){
            $type='alumni';
            $url="alumni/index.php";
        }

            //$row=mysql_fetch_array($result);

        if( $type) {
            $_SESSION['user_name']=$username;
            $_SESSION['pass']=$password;
            $_SESSION['type']=$type;
            $a['stat']=1;
            $a['url']=$url;
        }else{
            $a['stat']=0;
            $a['sql']=$sql;
        }

            $json=json_encode($a);

    die($json);

    }
}
                //include "menu.php";
            ?>
<script src="http://code.jquery.com/jquery-1.9.1.min.js"></script>
            <div id="isi_content">
                <p>
                    <h3>Form Login</h3>
                    <div id="login">
                        <form action="proses_login2.php" method="post" id="myForm">
                            <table id="form_login">
                                <tr>
                                    <td>Username</td>
                                    <td><input type="text" name="username" /></td>
                                </tr>
                                <tr>
                                    <td>Password</td>
                                    <td><input type="password" name="pass"/></td>
                                </tr>
                                <tr>

                                    <td colspan="2" ><input name="Button" type="submit"  class="Button" value="Masuak"
                                    onclick="checkLogin();return false"
                                    />
                                    <a href="index.php?modul=daftar">Mendaftar</a></td>
                                </tr>
                            </table>
                        </form>
                    </div>
                </p>
            </div><!-- end isi Content -->
<script>
function checkLogin()
{
 var selectorform = 'form#myForm';
        var datax = $(selectorform).serialize();
/*
Ganti URL dengan alamat check login
*/
        var request = $.ajax({
          url: "?act=check",
          type: "POST",
          data: datax,
          dataType: "json"
    });

        request.success(function(msg) {
          console.log('data sudah terkirim');
                if(msg.stat==0)
                {
                        alert('periksa kembali user anda');
                        $(".msg").append(msg.sql);
                        return false;
                }else{
                        alert('terima kasih atas loginnya');
                        window.location.href =msg.url;
                }

        });
}
</script>
<div class='msg'></div>
<!--script yg di paling atas bs di pindah.. -->