无限滚动php张贴重复

我将此代码用于具有无限滚动的php脚本，但我遇到了一个问题。当我向下滚动帖子重复到无限时，我没有得到"不再发布帖子"的消息。例如，如果我在数据库中有10个帖子，并且限制为5，当我向下滚动显示其他5个帖子并得到一条消息"不再发布帖子"时。

<?php
// Connect do DB
try {
    $conn = new PDO('mysql:host=localhost;dbname=fb','root','');
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
}
catch (PDOException $e) {
    die('ERROR: ' . $e->getMessage());
}
// Pagination
$limit = 4;
$total = $conn->query("SELECT COUNT(*) FROM posts")->fetchColumn();
$pages = ceil($total / $limit);
$page = min($pages, filter_input(INPUT_GET, 'page', FILTER_VALIDATE_INT, array(
'options' => array(
'default'   => 1,
'min_range' => 1,
),
)));
$offset = ($page - 1) * $limit;
$sql = "SELECT * FROM posts ORDER BY id DESC LIMIT 5 OFFSET $offset";
?>
<center>
<div class="posts-container">
<?php foreach ($conn->query($sql) as $post) { ?>
<div class="posts" style="width: 400px">
    <h1>
    <?= $post['id']; ?>
    </h1>
    <p>
    <?= $post['body']; ?>
    </p>
</div>
<?php } 
if ($page < $pages) { 
?>
<nav id="page-nav">
    <a href='index.php?page=<?= ($page + 1) ?>'>Next >></a>
</nav>
<?php } ?>
</div>
</center>
</div>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.js"></script>
<script type="text/javascript" src="http://www.infinite-scroll.com/wp-content/plugins/infinite-scroll/jquery.infinitescroll.js"></script>
<script>
$('.posts-container').infinitescroll({
    navSelector     : "#page-nav",
    nextSelector    : "#page-nav a",
    itemSelector    : ".posts",
}, function(newElements, data, url){
});
</script>