Счётчик новых сообщений [jQuery]

$count = mysql_result(mysql_query('SELECT COUNT(`id`) FROM `mail_mess` WHERE `to_id` = "'.$user['id'].'" AND `read` = "0"'),0);
?>
 
Новых сообщений: <span id="count_mess"><?=$count; ?></span><br />
 
<script type="text/javascript" src="javascript/refresh_count_mess.js"></script>
 
Файл javascript/refresh_count_mess.js
$(function() {
setInterval('refresh_count_mess()', 1500);
});
 
function refresh_count_mess() {
$.ajax({
url: "javascript/refresh_count_mess.php",
cache: false,
dataType: "json",
success: function(result) {
$('#count_mess').html(result.count);
}
});
}
 
Файл: javascript/refresh_count_mess.php
<?php
require_once 'engine/connect.php'; // Подключение к бд
require_once 'engine/core.php'; // Настройки пользователя и т.п.
 
if (isset($user)) $count = mysql_result(mysql_query('SELECT COUNT(`id`) FROM `mail_mess` WHERE `to_id` = "'.$user['id'].'" AND `read` = "0"'),0);
else $count = 0;
 
$result = array('count' => $count);
echo json_encode($result);