///form:///

<form id='loginform' name='loginform' action='' method='post' >
user name:<input class='required' name='myusername' type='text' id='myusername'><br />
password:<input class='required' name='mypassword' type='password' id='mypassword' /><br />
<input id='loginbutton' class='button' type='button' name='Submit' value='Login' />
</form>
<p class='response_msg'></p>




///scipt:///

	$('#loginbutton').click(function() {

		$('#loginform').ajaxSubmit({
			url: 'checklogin.php',
			type: 'POST',
			success: function(responseText, statusText, xhr, $form) {
				responseText = jQuery.trim(responseText);

				if(responseText === "SUCCESS")
					window.location = "index.php?site=login_success";
				else
				{
					$('#loginbox .response_msg').html(responseText);
				}
			}
		});
	});



checklogin:

<?php

/*
@session_start();
include_once "func.php";
include_once "connect.php";
if(isset($_POST['myusername']))
{
	if(isset($_POST['mypassword']))
	{
		$user = filter_var($_POST['myusername'], FILTER_SANITIZE_STRING);
		$query = mysql_query("SELECT * FROM user WHERE username='$user'") or die(mysql_error());
		if(mysql_num_rows($query) == 0)
			die("Fel user / pass");
		$result = mysql_fetch_assoc($query);
		$pass = md5($_POST['mypassword'].$result['salt']);
		if(strcmp($pass, $result['password']) == 0)
		{
			$_SESSION['loggedIn']= true;
			$_SESSION['user'] =  $variable['username'];
			$_SESSION['userid'] =  $variable['userid'];
			die("SUCCESS");
		}
		else
			die("Fel user / pass.");
	}
	header("Location:index.php");
}
header("Location:index.php");
*/


@session_start();
ob_start();
include_once "connect.php";
$tbl_name = "user";


// Define $myusername and $mypassword
$myusername=$_POST['myusername'];
$mypassword=$_POST['mypassword'];

// To protect MySQL injection (more detail about MySQL injection)
$myusername = stripslashes($myusername);
$mypassword = stripslashes($mypassword);
$myusername = mysql_real_escape_string($myusername);
$mypassword = mysql_real_escape_string($mypassword);

$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";
$result=mysql_query($sql);

$variable = mysql_fetch_assoc($result);



// Mysql_num_row is counting table row
$count=mysql_num_rows($result);
// If result matched $myusername and $mypassword, table row must be 1 row

if($count==1){
// Register $myusername, $mypassword and redirect to file "login_success.php"
$_SESSION['loggedIn']= true;
$_SESSION['user'] =  $variable['username'];
$_SESSION['userid'] =  $variable['userid'];
//$_SESSION['user'] = $result['username'];

die("SUCCESS");


//header("location:index.php?site=login_success");
}
else {
die("something was wrong!");
//echo "wrong username or password. Try again!";
}

ob_end_flush();

?>