HTML部分============================================================================================
<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta http-equiv="X-UA-Compatible" content="ie=edge" />
<script src="../bootstrap/js/jquery-3.3.1.min.js" type="text/javascript" charset="utf-8"></script>
<title>Document</title>
</head>
<body>
<div class="sanji"></div>
</body>
</html>
<script type="text/javascript">
// 入口函数
$(document).ready(function(){
var attr = "<select id = 'sheng'></select><select id = 'shi'></select><select id = 'qu'></select>";
$(".sanji").html(attr);
sheng();
// 通过下拉菜单#sheng的change事件触发函数shi()和qu()
$("#sheng").change(function(){
shi();
qu();
});
$("#shi").change(function(){
qu();
})
})
function sheng(){
// 省的编号都为0，没有父级
var myid = "0";
var shengstr = "";
$.ajax({
type:"post",
url:"sjldcl.php",
async:true,
data:{
myid:myid
},
dataType:"json",
success:function(data){
for (var i =0;i<data.length;i++) {
shengstr +="<option value = '"+data[i][0]+"'>"+data[i][1]+"</option>";
}
$("#sheng").html(shengstr);
// 在此处调用函数shi()是因为执行完函数sheng()才可获得#sheng元素的value值
// 如果想把函数shi()放到入口函数中，则需要把$.ajax的async改为false
// 执行完函数sheng()获得#sheng的value值后再执行函数shi()
shi();
}
});
}
function shi(){
// 获取#sheng的value值，为#shi的编号
var myid = $("#sheng").val();
var shistr = "";
$.ajax({
type:"post",
url:"sjldcl.php",
async:true,
data:{
myid:myid
},
dataType:"json",
success:function(data){
for (var i =0;i<data.length;i++) {
shistr +="<option value = '"+data[i][0]+"'>"+data[i][1]+"</option>";
}
$("#shi").html(shistr);
qu();
}
});
}
function qu(){
// 获取#shi的value值，为#qu的编号
var myid = $("#shi").val();
var qustr = "";
$.ajax({
type:"post",
url:"sjldcl.php",
async:true,
data:{
myid:myid
},
dataType:"json",
success:function(data){
for (var i =0;i<data.length;i++) {
qustr +="<option value = '"+data[i][0]+"'>"+data[i][1]+"</option>";
}
$("#qu").html(qustr);
}
});
}
</script>
HTML部分^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
PHP部分============================================================================================
<?php
$conn = new mysqli("localhost","root","","ceshi2");
$conn->connect_error?die():"";
$myid = $_POST['myid'];
$sql = "select * from dt_area where area_parent_id = {$myid}";
$resule = $conn->query($sql);
$attr = $resule->fetch_all();
echo json_encode($attr);
?>
PHP部分^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^