login pake session

<?php
session_start();
$c=mysql_connect("localhost","root","password") or die(mysql_error());
/*
Biasanya root trus tanpa password
*/
mysql_select_db("bukutamu");

$uname_admin= $_POST['uname_admin'];
$pswd_admin = $_POST['pswd_admin'];
$query="SELECT * FROM admin WHERE uname_admin='$uname_admin' AND
pswd_admin='$pswd_admin'";
$hasil=mysql_query($query) or die("Query Error : ".mysql_error());
/*
 jika id admin ditemukan dan password
benar
*/
if(mysql_num_rows($hasil)==1)
{
    $data=mysql_fetch_array($hasil);
    session_register("uname_admin","pswd_admin");
    $_SESSION['uname_admin']=$data['uname_admin'];
    $_SESSION['pswd_admin']=$data['pswd_admin'];
    ?>
    <b><script language="JavaScript">alert('Selamat datang di
    halaman Administrator');
    document.location='../Admin/admin_home.php'</script></b>
    <?php
}
else
{
    ?><script language="JavaScript">
    alert('Username atau password Anda salah');
    document.location='../Admin/index.php';
    </script>
    <?php
}

/*
mulailah pake
mysqli
*/