<!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>

$(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);

		}

    });

}

<?php

$pcode = $_POST["pcode"];

require "DBDA.class.php";

$db = new DBDA();

$sql = "select * from chinastates where parentareacode='{$pcode}'";

echo $db->strquery($sql);

<?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;

		}

	}

}