主页面代码
<!DOCTYPE html><html lang="en"><head> ???<meta charset="UTF-8"> ???<title>Title</title> ???<script src="../wenjian/jquery-2.2.3.min.js"></script></head><body><select id="sheng"> ???<option>请选择</option></select><select id="shi"> ???<option >请选择</option></select><select id="qu"> ???<option >请选择</option></select></body></html><script> ???$.ajax({ ???????data: {parent_id: 0}, //发送的数据 ???????dataType: "json", //返回值的类型 text为string型 ???????type: ‘post‘, ??//发送请求的方法(get) ???????url: ‘sheng_l.php‘,//发送请求的地址 ???????success: function (data) {//发送成功时的回调函数 ???// ???????????console.log(data); ???????????for (var i in data) { ???????????????$("#sheng").append("<option value=‘"+ data[i][2] +"‘>" + data[i][1] ?+"</option>") ???????????} ???????} ???}) ???$(document).ready(function () { ???????$("#sheng").change(function () { ???????????$("#shi").get(0).options.length= 1;// ???????????$("#qu").get(0).options.length= 1; ???????????var data = $("#sheng").find("option:selected").val(); ???????????$.ajax({ ???????????????data:{parent_id:data}, ???????????????type:"post", ???????????????dataType:"json", ???????????????url:"sheng_l.php", ???????????????success:function (data) { ???????????????????for(var i in data){ ???????????????????????$("#shi").append("<option value=‘" + data[i][2] +"‘>" + data[i][1] +"</option>") ???????????????????} ???????????????} ???????????}) ???????}) ???}) ???$(document).ready(function () { ???????$("#shi").change(function () { ???????????$("#qu").get(0).options.length= 1; ???????????var data = $("#shi").find("option:selected").val(); ???????????$.ajax({ ???????????????data:{parent_id:data}, ???????????????type:"post", ???????????????dataType:"json", ???????????????url:"sheng_l.php", ???????????????success:function (data) { ???????????????????for (var i in data){ ???????????????????????$("#qu").append("<option value=‘" +data[i][2] +"‘>" +data[i][1] +"</option>") ???????????????????} ???????????????} ???????????}) ???????}) ???})处理页面代码
<?php/** * Created by fcc * User: Administrator * Date: 2017/10/29 * Time: 20:56 */require_once "../wenjian/DBDA.class.php";$db = new DBDA();$sql = "select * from region WHERE father_id = {$_POST[‘parent_id‘]}";$result = $db->Query($sql);echo json_encode($result);ajax 三级联动写法
原文地址：http://www.cnblogs.com/dej-11/p/7753176.html