三级联动实例

全国省市县查询

html代码

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>无标题文档</title>
    <script src="../jquery-1.11.2.min.js"></script>
    <script src="sanji.js"></script>
</head>
 
<body>
    <h1>区域查询</h1>
    <div id="sanji"></div>
</body>
</html>

js代码实现各区市随省的变化而变化

$(document).ready(function(e) {
    $("#sanji").html("<select id='sheng'></select><select id='shi'></select><select id='qu'></select>");//将三个下拉的字符串交给前边的div
    tiansheng();//加载省的数据
    tianshi();//加载市的数据
    tianqu();//加载区 的数据
     
    $("#sheng").change(function(){//变化后执行               
        tianshi();//重新加载市
        tianqu();//重新加载区
    })
    $("#shi").change(function(){//变化后执行
        tianqu();//加载区的数据
    })
});
 
function tiansheng(){
    var pcode = "0001"; //找出省的父级代号
    $.ajax({
        async:false,//同步加载
        url:"states.php",
        data:{pcode:pcode},
        type:"POST",
        dataType:"TEXT",
        success: function(data){            
        var hang = data.split("|");//拆分行  
        var str = "";
            for(var i=0;i<hang.length;i++){
                var lie = hang[i].split("^");//拆分列        
                str += "<option value='"+lie[0]+"'>"+lie[1]+"</option>";   
            }
            $("#sheng").html(str);
        }
    });
}
 
function tianshi(){
    var pcode = $("#sheng").val();//找市的父级代号，省选中项的值
    $.ajax({
        async:false,//同步加载
        url:"states.php",
        data:{pcode:pcode},
        type:"POST",
        dataType:"TEXT",
        success: function(data){
            var hang = data.split("|");
            var str = "";
            for(var i=0;i<hang.length;i++){
                var lie = hang[i].split("^");
                str += "<option value='"+lie[0]+"'>"+lie[1]+"</option>";
            }
            $("#shi").html(str);
        }
    });
}
 
function tianqu(){
    var pcode = $("#shi").val();//找区的父级代号，市选中项的值
    $.ajax({
        url:"states.php",
        data:{pcode:pcode},
        type:"POST",
        dataType:"TEXT",
        success: function(data){
            var hang = data.split("|");
            var str = "";
                for(var i=0;i<hang.length;i++){
                    var lie = hang[i].split("^");
                    str += "<option value='"+lie[0]+"'>"+lie[1]+"</option>";
                }
                $("#qu").html(str);
        }
    });
}

　　处理页面

<?php
$pcode = $_POST["pcode"];
require "DBDA.class.php";
$db = new DBDA();
$sql = "select * from chinastates where parentareacode='{$pcode}'";
echo $db->strquery($sql);

DBDA封装功能

<?php
class DBDA{
    public $host="localhost"; //服务器地址
    public $uid="root"; //用户名
    public $pwd="123"; //密码
    public $dbname="crud"; //数据库名称
    public function query($sql,$type=0){
        $db = new MySQLi($this->host,$this->uid,$this->pwd,$this->dbname);
        $result = $db->query($sql);
        if($type){
            return $result;
        }else{
            return $result->fetch_all();
        }
    }
    public function strquery($sql,$type=0){
        $db = new MySQLi($this->host,$this->uid,$this->pwd,$this->dbname);
        $result = $db->query($sql);
        if($type){
            return $result;
        }else{
            $arr = $result->fetch_all();
            $str ="";
            foreach($arr as $v){
                $str .= implode("^",$v)."|";
            }
            $str = substr($str,0,strlen($str)-1);
            return $str;
        }
    }
}