php+ajax+jquery实现点击加载更多内容

<script type="text/javascript" src="jquery.js"></script> 
<script type="text/javascript" src="jquery.more.js"></script> 

<div id="more"> 
   <div class="single_item"> 
      <div class="element_head"> 
        <div class="date"></div> 
        <div class="author"></div> 
      </div> 
      <div class="content"></div> 
   </div> 
   <a href="javascript:;" class="get_more">::点击加载更多内容::</a> 
</div> 

#more{margin:10px auto;width: 560px; border: 1px solid #999;}        
.single_item{padding: 20px; border-bottom: 1px dotted #d3d3d3;} 
.author{position: absolute; left: 0px; font-weight:bold; color:#39f} 
.date{position: absolute; right: 0px; color:#999} 
.content{line-height:20px; word-break: break-all;} 
.element_head{width: 100%; position: relative; height: 20px;} 
.get_more{margin:10px; text-align:center} 
.more_loader_spinner{width:20px; height:20px; margin:10px auto; background: url(loader.gif) 
 no-repeat;} 

$(function(){ 
  $('#more').more({'address': 'data.php'}) 
}); 

require_once('connect.php'); 
 
$last = $_POST['last']; 
$amount = $_POST['amount']; 
 
$user = array('demo1','demo2','demo3','demo3','demo4'); 
$query=mysql_query("select * from say order by id desc limit $last,$amount"); 
while ($row=mysql_fetch_array($query)) { 
  $sayList[] = array( 
    'content'=>$row['content'], 
    'author'=>$user[$row['userid']], 
    'date'=>date('m-d H:i',$row['addtime']) 
   ); 
} 
echo json_encode($sayList);