基于AJAX的无限滚动-不适用于以DESC顺序排序的Mysql记录
[英]AJAX based infinite scrolling - does not work for Mysql records sorted in DESC order
问题描述
我正在使用此处提供的代码段
我的PHP代码是：
<?PHP
/*** This is for bottomless listing of record from a table ****/
$sql = 'SELECT * FROM agency_list ORDER BY id DESC LIMIT 0, 5';
$query = $dbo4->prepare($sql); // dbo4 coming from config.php
$query->execute();
$list = $query->fetchAll();
?>
相关的css代码是：
.content {
padding: 10px;
min-height: 100px;
text-align: center;
}
#loader {
text-align: center;
display: none;
}
#items {
list-style: none;
text-align: left;
}
#items li {
margin: 0 0 10px 0;
background: #FFFFFF; /* original -- f1f0f0*/
border: 1px solid #999999;
border-radius: 5px;
color: #333333;
}
#items li h2 {
font-size: 18px;
padding: 5px;
}
#items li p {
padding: 5px;
}
java脚本代码（end-less-scroll.js）如下：
var is_loading = false; // initialize is_loading by false to accept new loading
var limit = 5; // limit items per page
$(function() {
$(window).scroll(function() {
if($(window).scrollTop() + $(window).height() == $(document).height()) {
if (is_loading == false) { // stop loading many times for the same page
// set is_loading to true to refuse new loading
is_loading = true;
// display the waiting loader
$('#loader').show();
// execute an ajax query to load more statments
$.ajax({
url: 'load_more.php',
type: 'POST',
data: {last_id:last_id, limit:limit},
success:function(data){
// now we have the response, so hide the loader
$('#loader').hide();
// append: add the new statments to the existing data
$('#items').append(data);
// set is_loading to false to accept new loading
is_loading = false;
}
});
}
}
});
});
上面的代码调用了具有以下代码的load_more.php：
<?PHP
include 'config.php';
$last_id = $_POST['last_id'];
$limit = 5;
if (isset($_POST['limit']))
{
$limit = intval($_POST['limit']);
}
// selecting the items for page params
try
{
$sql = 'SELECT * FROM agency_list WHERE id > :last_id ORDER BY id DESC LIMIT 0, :limit';
$query = $dbo4->prepare($sql);
$query->bindParam(':last_id', $last_id, PDO::PARAM_INT);
$query->bindParam(':limit', $limit, PDO::PARAM_INT);
$query->execute();
$list = $query->fetchAll();
}
catch (PDOException $e)
{
echo 'PDOException : '. $e->getMessage();
}
$last_id = 0;
foreach ($list as $rs)
{
$last_id = $rs['id'];
?>
<li>
<h2> <a href='#'><?PHP echo '[' .$rs['id'] .'] ' . $rs['agency_nm']; ?></a>
<img height = "32px" width = "32px" src="images/face_smile_1.png"></h2>
<blockquote>
<p>
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Et non ex maxima parte de tota iudicabis?
Item de contrariis, a quibus ad genera formasque generum venerunt. Sit enim idem caecus, debilis.
Duo Reges: constructio interrete.
<BR>
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Et non ex maxima parte de tota iudicabis?
Item de contrariis, a quibus ad genera formasque generum venerunt. Sit enim idem caecus, debilis.
Duo Reges: constructio interrete.
</p>
</blockquote>
<h5> <?PHP echo $rs['agency_addr_landmark']; ?></h5>
<h5> <?PHP echo $rs['agency_city']. ' - ' . $rs['agency_pin'] . ' [' . $rs['agency_state'] . '] ' ; ?></h5>
<h5> <?PHP echo $rs['agency_contact_per_1']; ?></h5>
<h5> <font color = "maroon"><?PHP echo $rs['agency_contact_addr1'];?></font></h5>
<p style="align:right;">
<a href="#" class="tags" style="background-color:darkgreen;">Details</a>
<a href="#" class="tags" style="background-color:#955251;">Update</a>
<a href="#" class="tags" style="background-color:#5B5EA6;">More</a>
</p>
<BR>
</li>
<BR>
<?PHP
}
if ($last_id != 0)
{
echo '<script type="text/javascript">var last_id = '.$last_id.';</script>';
}
// sleep for 1 second to see loader, it must be deleted in prodection
sleep(1);
?>
最后，提取的记录将在此div中列出（在HTML文件中）
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>
<script type="text/javascript" src="js/end-less-scroll.js"></script>
<div class="row">
<div class="twelve columns">
<div class="content">
<ul id="items">
<?PHP
$last_id = 0;
foreach ($list as $rs)
{
$last_id = $rs['id']; // keep the last id for the paging
?>
<li>
<h2> <a href='#'><?PHP echo '[' .$rs['id'] .'] ' . $rs['agency_nm']; ?></a><img height = "32px" width = "32px" src="images/face_smile_1.png"></h2>
<blockquote>
<p>
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Et non ex maxima parte de tota iudicabis? Item de contrariis, a quibus ad genera formasque generum venerunt. Sit enim idem caecus, debilis. Duo Reges: constructio interrete.
<BR>
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Et non ex maxima parte de tota iudicabis? Item de contrariis, a quibus ad genera formasque generum venerunt. Sit enim idem caecus, debilis. Duo Reges: constructio interrete.
</p>
</blockquote>
<h5> <?PHP echo $rs['agency_addr_landmark']; ?></h5>
<h5> <?PHP echo $rs['agency_city']. ' - ' . $rs['agency_pin'] . ' [' . $rs['agency_state'] . '] ' ; ?></h5>
<h5> <?PHP echo $rs['agency_contact_per_1']; ?></h5>
<h5> <font color = "maroon"><?PHP echo $rs['agency_contact_addr1'];?></font></h5>
<p style="align:right;">
<a href="#" class="tags" style="background-color:darkgreen;">Details</a>
<a href="#" class="tags" style="background-color:#955251;">Update</a>
<a href="#" class="tags" style="background-color:#5B5EA6;">More</a>
</p>
<BR>
</li>
<BR>
<?PHP
}
?>
<script type="text/javascript">var last_id = <?PHP echo $last_id; ?>;</script>
</ul>
<!-- this is the paging loader, now is hidden, it wiil be shown when we scroll to bottom -->
<p id="loader"><img src="images/ajax-loader.gif"></p>
</div><!-- content -->
<hr>
</div>
</div>
我的问题是
（1）如果我在给出的两个MySQL查询中按ASC顺序对记录进行排序，则代码工作正常。 但是，如果我将排序顺序从ASC（如链接教程中给出的）更改为DESC，则逻辑仅列出5条记录，然后再次列出第4,3,2,1条记录并停止工作。 我知道我在逻辑上做得很愚蠢，但却找不到我的错误。 请帮我。
（2）假设我需要按其他一些列排序（这不是PRIMARY键 - 这里是id PRIMARY KEY），例如假设我想通过agency_nm对记录进行排序，并将它们列在底部少列表方式中，我是否应该在AJAX部分（或load_more.php）中进行一些更改？ 抱歉，但是我对AJAX的了解并不好-因此这个愚蠢的问题。
感谢/向大家致以亲切的帮助和建议。
1 个解决方案
解决方案1
0 2016-10-31 09:18:00
换行：
$sql = 'SELECT * FROM agency_list WHERE id > :last_id ORDER BY id DESC LIMIT 0, :limit';
$sql = 'SELECT * FROM agency_list WHERE id < :last_id ORDER BY id DESC LIMIT 0, :limit';
您所要做的就是更改此运算符：> to <
Mysql Innodb不会使用desc顺序返回select的最后一行
[英]Mysql Innodb does not return the last row on select with desc order
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