jQuery+PHP+MySQL实现无限级联下拉框效果_jquery

<?php
  header("Content-type: text/html; charset=utf-8"); 

  //数据库连接操作
  $conn = mysql_connect("localhost","Zjmainstay","") or die("Can not connect to database.Fatal error handle by ". __FILE__);
  mysql_select_db("test",$conn);      //数据库名为 test
  mysql_query("SET NAMES utf8",$conn);
  
  //获取父级id
  $pid = (int)$_POST['pid'];
  
  //查询子级
  $sql = "SELECT id,text FROM `wuxianjilian` WHERE pid={$pid}";
  $result = mysql_query($sql,$conn);
  
  //组装子级下拉菜单
  $html = '';
  while($row = mysql_fetch_assoc($result)){
    $html .= ''.$row['text'].'';
  }

  if(!empty($html)) $html = '请选择' . $html . '';
  
  //输出下拉菜单
  echo json_encode($html);
//End_php

wuxianjilian.sql
/*
Navicat MySQL Data Transfer

Source Server     : localhost
Source Server Version : 50516
Source Host      : localhost:3306
Source Database    : test

Target Server Type  : MYSQL
Target Server Version : 50516
File Encoding     : 65001

Date: 2012-10-24 20:59:09
*/

SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for `wuxianjilian`
-- ----------------------------
DROP TABLE IF EXISTS `wuxianjilian`;
CREATE TABLE `wuxianjilian` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `pid` int(11) DEFAULT NULL,
 `text` varchar(32) DEFAULT NULL,
 PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=22 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of wuxianjilian
-- ----------------------------
INSERT INTO `wuxianjilian` VALUES ('1', '0', 'A0');
INSERT INTO `wuxianjilian` VALUES ('2', '0', 'B0');
INSERT INTO `wuxianjilian` VALUES ('3', '1', 'C1');
INSERT INTO `wuxianjilian` VALUES ('4', '1', 'D1');
INSERT INTO `wuxianjilian` VALUES ('5', '1', 'E1');
INSERT INTO `wuxianjilian` VALUES ('6', '2', 'F2');
INSERT INTO `wuxianjilian` VALUES ('7', '2', 'G2');
INSERT INTO `wuxianjilian` VALUES ('8', '3', 'H3');
INSERT INTO `wuxianjilian` VALUES ('9', '3', 'I3');
INSERT INTO `wuxianjilian` VALUES ('10', '3', 'J3');
INSERT INTO `wuxianjilian` VALUES ('11', '3', 'K3');
INSERT INTO `wuxianjilian` VALUES ('12', '4', 'L4');
INSERT INTO `wuxianjilian` VALUES ('13', '4', 'M4');
INSERT INTO `wuxianjilian` VALUES ('14', '8', 'N8');
INSERT INTO `wuxianjilian` VALUES ('15', '9', 'N9');
INSERT INTO `wuxianjilian` VALUES ('16', '14', 'O14');
INSERT INTO `wuxianjilian` VALUES ('17', '14', 'P14');
INSERT INTO `wuxianjilian` VALUES ('18', '14', 'Q14');
INSERT INTO `wuxianjilian` VALUES ('19', '17', 'R17');
INSERT INTO `wuxianjilian` VALUES ('20', '17', 'S18');
INSERT INTO `wuxianjilian` VALUES ('21', '20', 'T20');