设计模式：ajax实现，数据库格式：id,name,parent_id
数据库：
CREATE TABLE IF NOT EXISTS `city` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(30) DEFAULT NULL,
`parent_id` int(11) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=26 ;INSERT INTO `city` (`id`, `name`, `parent_id`) VALUES
(1, '安徽', 0),
(2, '浙江', 0),
(3, '亳州', 1),
(4, '合肥', 1),
(5, '巢湖', 1),
(6, '涡阳', 3),
(7, '蒙城', 3),
(8, '利辛', 3),
(9, '谯城', 3),
(10, '杭州', 2),
(11, '宁波', 2),
(12, '温州', 2),
(13, '义乌', 2),
(14, '嘉兴', 2),
(15, '巢湖', 4),
(16, '阜阳', 1),
(17, '界首', 16),
(18, '泥鳅', 16),
(19, '拱墅区', 10),
(20, '江干区', 10),
(21, '临湖镇', 6),
(22, '立德镇', 5),
(23, '标里镇', 6),
(24, '花沟镇', 6),
(25, '义门镇', 6);
HTML代码：
<html>
<head>
<meta http-equiv="content-type" content="text/html" charset="utf-8">
<style type="text/css">
h2{
text-align:center;
color:red;
}
.div{
width:500px;
height:300px;
border:1px solid gray;
margin:auto;
text-align:center;
padding-top:30px;
}
.div select{
width:80px;
height:25px;
color:green;
}
</style>
</head><script type="text/javascript">function deal(value,next){
var Next=document.getElementById(next); //删除节点
var oP=Next.getElementsByTagName("option");
for(var i=oP.length-1;i>=1;i--){
oP[i].parentNode.removeChild(oP[i]);
} //创建ajax引擎
var xmlhttp="";
if(window.XMLHttpRequest){
xmlhttp=new XMLHttpRequest();
}else{
xmlhttp=new ActiveXObject("Microsoft.XMLHttp");
} //判断状态是否满足条件
xmlhttp.onreadystatechange=function(){
if(xmlhttp.readyState==4&&xmlhttp.status==200){
var val=xmlhttp.responseText;
// alert(val);
var object=eval("("+val+")");
for(var k in object){
//创建节点
var oPt=document.createElement("option");
//添加属性和值
oPt.setAttribute('value',object[k]['name']);
Next.appendChild(oPt);
oPt.innerHTML=object[k]['name'];
}
}
}
var url="deal.php";
var data="name="+value;
//打开
xmlhttp.open("post",url,true); xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");//必须加上
//发送数据
xmlhttp.send(data);
}window.onload=function(){ deal(null,"sheng");
}
</script><body>
<h2>省市联动AJAX实现</h2>
<div class="div">
<form action="Act.php" method="post">
<!-- 省级标签 -->
<select name="sheng" id="sheng" onchange="deal(this.value,'shi')">
<option>省</option>
</select> <!-- 市级标签 -->
<select name="shi" id="shi" onchange="deal(this.value,'xian')">
<option>市</option>
</select> <!-- 县级标签 -->
<select name="xian" id="xian" onchange="deal(this.value,'zhen')">
<option>县</option>
</select> <!-- 镇级标签 -->
<select name="zhen" id="zhen">
<option>镇</option>
</select>
<input type="submit" value="提交"/>
</form>
</div></body></html>
php后台处理：
<?php
header("content-type:text/html;charset=utf-8");$name=$_POST['name'];//连接数据库
$conn=mysqli_connect("localhost","root","");
if(!$conn){
die("连接数据库失败");
}//设置字符集
mysqli_query($conn, "set names utf8");//选择数据库
mysqli_select_db($conn, "city");$sql="select id from city where name="."'$name';";$res=mysqli_query($conn, $sql);
if(mysqli_num_rows($res)>0){
$row=mysqli_fetch_assoc($res);
$id=$row['id'];
}else{
$id=0;
}$sql="select * from city where parent_id=".$id;$res=mysqli_query($conn, $sql);
$arr=array();
if(mysqli_num_rows($res)>0){
while($row=mysqli_fetch_assoc($res)){
$arr[]=$row;
}
}foreach ($arr as $k=>$v){ @$str.='{"name":'.'"'.$v['name'].'","parent_id":'.'"'.$v['parent_id'].'","id":'.'"'.$v['id'].'"},';}echo "[".$str."]";// echo '[{"name":"安徽","parent_id":"0"},{"name":"浙江","parent_id":"0"},{"name":"吉林","parent_id":"0"},]';?>
实现效果：
