Detailed explanation of ajax paging query graphic and text

This time I will bring you a detailed graphic and text explanation of ajax paging query. What are the precautions for ajax paging query? . The following is a practical case, let’s take a look.

(1) First write a page to display data. How many parts are needed for paging query?

1. First is the query text box input, and the query button, then start writing the code

<p>
<input type="text" id="key" /> //输入查询字的文本框
<input type="button" value="查询" id="chaxun" /> //查询按钮，起名字是为了以后给这个按钮加事件，因为只有点击了才可以将文本框的内容进行查询
</p>

Look at the effect:

2. The next step is to display the data. To display the data, you must check the database, and you must use the ajax method

First introduce the jQuery package into the page that displays data

<script src="../jquery-1.11.2.min.js"></script> // Introduce the jQuery package

To write the contents of the columns you want to display, you naturally need to write a table. Write a row. There are cells in the row to put the field names you want to display (three types are shown here. Information)

<table width="50%" border="1" cellpadding="0" cellspacing="0">
　　<tr><br>　　　　//显示的字段名，这是第一行的内容
  <td>代号</td>
  <td>名称</td>
  <td>父级代号</td>
　　</tr>
　　<tbody id="bg>
<br>　　//这里放的就是查找数据库的内容了
 </tbody>
  
</table>

I haven’t checked the database yet, but you can check the display first:

3. Now you can check the database first , ajax will be used here

3.1 But since it is to be displayed in pages, there will be a default first page, you can set a variable first

var page = 1; //Current page

3.2 Then start writing ajax and query the database, but this will be commonly used To avoid writing it many times, we can write a method

function Load()
{
　　var key = $("#key").val(); //查询条件：因为会用到查询
　　$.ajax({
 url:"fenye_chuli.php", //显示数据的处理页面
 data:{page:page,key:key}, //页数和查询都要传值
 type:"POST",
 dataType:"JSON", //这里我们用JSON的数据格式
 success: function(data){
  //执行完处理页面后写代码
  }
 });
}

3.3 Then write the processing page that displays the data. What needs to be considered here is how many items to skip. The data also includes how many pieces of data you want to display

<?php
include("DBDA.class.php"); //调用封装好的类
$db = new DBDA(); //造新对象
$page = $_POST["page"]; //传值页数
$key = $_POST["key"]; //传值关键字<br>
$num = 20; //每页想要显示的数据条数
$tiao = ($page-1)*$num; //显示的当前跳过多少条数据
//查询表中模糊查询名称是关键字，分页是跳过多少条，显示多少条数据
$sql = "select * from chinastates where areaname like '%{$key}%' limit {$tiao},{$num}";
//执行sql语句
echo $db->JSONQuery($sql); //调用的是写好的JSON数据格式的处理方式

The JSON data format is an associative array, so you need to process it and encapsulate the processing method into a class

The processing method is written in "dataType (data format) in AJAX - text, json"

3.4 After processing the page, you need to write the code after executing the page in ajax (Note: The above uses the JSON data format, so please note that the field name must be the same as that in the database, and it is an associative array)

success: function(data){
 var str = "";
 for(var k in data)
 {<br>　　　　　　　//循环显示的代号、名称、父级代号
 　　str +="<tr><td>"+data[k].AreaCode+"</td><td>"+data[k].AreaName+"</td><td>"+data[k].ParentAreaCode+"</td></tr>";
 }
 $("#bg").html(str); //将内容放大显示这些数据的地方
}

This way you want The displayed data is placed in bg. Remember to call this method

#. Now the data is displayed, but paging cannot be achieved in this way, so paging is still needed. Here is You have to put numbers, but they also need to be traversed. You can just put them empty

<p id="xinxi">
　　//显示数字或是上一页
</p>

3.5 This can also be written as a method, and then called

To know the maximum number of pages that can be displayed, you can first define a default maximum number. This maximum number can also be the maximum number of pages displayed when searching for keywords

var maxys = 1;

Find the value of the keyword

var key = $("#key").val();

Then write ajax, Check the total number of pages

$.ajax({
 async:false, //因为这个是要同步执行的，所以值是false
 url:"fenye_zys.php", //处理页面
 data:{key:key}, //想要传的值
 type:"POST", //传值方式
 dataType:"TEXT", //这里可以用TEXT字符串的方式
 success: function(d){
   //处理页面结束后的语句
 }
});

The next step is to write the processing page of the processing information

<?php
include("DBDA.class.php"); //调用封装好的类
$db = new DBDA();
$key = $_POST["key"]; //将值传过来
$num = 20; //默认显示的条数
$sql = "select count(*) from chinastates where areaname like &#39;%{$key}%&#39;"; //通过关键字查询总条数
$zts = $db->StrQuery($sql);
echo ceil($zts/$num); //转换成整数

After the processing page is executed, the maximum number of pages found must be handed over to the default maximum page Number

success: function(d){
 maxys = d; //将执行结果交给定义的最大页数
}

After this, there must be "previous page" and "next page". The middle number can display 5 items each time

str += "<span>总共："+maxys+"页</span> ";
str += "<span id=&#39;prev&#39;>上一页</span>"; //后面要用到单击事件的，在这起个名字
//循环的当前页
str += "<span id=&#39;next&#39;>下一页</span>"; //这个也是要用点击事件的也要起名字

and then write the page number of the cycle

for(var i=page-2;i<page+3;i++) //前后显示2个
{
　　if(i>=minys && i<=maxys) //页数是要有范围的，大于最小页数，小于最大页数
　　{
 if(i==page)
 {
 　　str += "<span class=&#39;dangqian&#39; bs=&#39;"+i+"&#39;>"+i+"</span> "; //当前页选中
 }
　　　　　else
　　　　　{
 　　str += "<span class=&#39;list&#39; bs=&#39;"+i+"&#39;>"+i+"</span> "; //显示当前页
　　　　　}
　　}
}

Transmit the value to xinxi of p

$("#xinxi").html(str);

The final result is as follows The picture shows:

The next step is the click event of the previous page and the next page, first the click event of the previous page

//给上一页添加点击事件
$("#prev").click(function(){
 page = page-1; //当前页减1
 if(page<1)
 {
 　　page=1;
 }
 Load(); //加载数据
 LoadXinXi(); //加载分页信息
})

and then Click event on the next page

//给下一页加点击事件
$("#next").click(function(){
 page = page+1; //当前页加1
 if(page>maxys) 
 {
 　　page=maxys;
 }
 Load(); //加载数据
 LoadXinXi(); //加载分页信息
})

Add click event to the number in the loop

//给中间的列表加事件
$(".list").click(function(){
 page = parseInt($(this).attr("bs"));
 Load(); //加载数据
 LoadXinXi(); //加载分页信息
})

最后都调用一下就可以了

4.关键字查询，这里就是要对查询进行加点击事件

("#chaxun").click(function(){
 page = 1;
 Load(); //加载数据
 LoadXinXi(); //加载分页信息
})

最后整体的显示：

这样分页查询解结束了，没有刷新页面就可以分页显示，看下整体的效果

（1）分页显示

（2）查询显示

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