About PHP+jQuery-ui Drag floating layer to sort and save to database instance

<script type="text/javascript" src="jquery.js"></script>  
<script type=&#39;text/javascript&#39; src=&#39;js/jquery-ui.min.js&#39;></script>
<div id="loader"></div>  
<div id="module_list">  
<input type="hidden" id="orderlist" value="<?php echo $sort; ?>" />  
   <!--?php 
                for ($i = 0; $i < $len; $i++) { 
                    ?-->  
   <div class="modules" title="<?php echo $sort_arr[$i]; ?>">  
    <h3 class="m_title">Module: 
     <!--?php echo $sort_arr[$i]; ?--></h3>  
    <p> 
     <!--?php echo $sort_arr[$i]; ?--></p>  
   </div>  
   <!--?php } ?-->  
   <div class="cl"></div>  
</div>

$(function() { 
    $(".m_title").bind('mouseover', 
    function() { 
        $(this).css("cursor", "move") 
    }); 
 
    var $show = $("#loader"); //进度条 
    var $orderlist = $("#orderlist"); 
    var $list = $("#module_list"); 
 
    $list.sortable({ 
        opacity: 0.6, 
        revert: true, 
        cursor: 'move', 
        handle: '.m_title', 
        update: function() { 
            var new_order = []; 
            $list.children(".modules").each(function() { 
                new_order.push(this.title); 
            }); 
            var newid = new_order.join(','); 
            var oldid = $orderlist.val(); 
            $.ajax({ 
                type: "post", 
                url: "update.php", 
                data: { 
                    id: newid, 
                    order: oldid 
                }, 
                //id:新的排列对应的ID,order：原排列顺序 
                beforeSend: function() { 
                    $show.html("<img  src=&#39;images/load.gif&#39; / alt="About PHP+jQuery-ui Drag floating layer to sort and save to database instance" > 正在更新"); 
                }, 
                success: function(msg) { 
                    $show.html(""); 
                } 
            }); 
        } 
    }); 
});

$order = $_POST['order']; 
$itemid = trim($_POST['id']); 
if (!empty($itemid)) { 
    if ($order != $itemid) { 
        $query = mysql_query("update sortlist set sort='$itemid' where id=1"); 
        if ($query) { 
            echo $itemid; 
        } else { 
            echo "none"; 
        } 
    } 
}