这类东西很多人都写过，但我是第一次写，支持一下菜鸟的原创吧～
第一级是写死的（因为省不会变的），以下三级都是现查的数据库，由于没有采用DIV格式，所以有些ID很长~
js代码：
1
function ProvinceChange(obj1,obj2,obj3)
2
{
3
if(typeof(ActiveXObject) != "undefined")
4
{
5 if(obj1.value=="")
6 {
7 obj2.length=0;
8 obj3.length=0;
9 form1.Wizard1_SchoolAddForm1_District.length=0;
10
}
11 else
12 {
13 xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
14 var item = obj1.options[obj1.selectedIndex].value;
15 var ReqStr = '<?xml version="1.0"?>';
16 xmlHttp.open("GET","SettleForm.aspx?province="+item);
17 xmlHttp.send(ReqStr);
18 xmlHttp.onreadystatechange = HandleResult;
19 }
20 }
21 function HandleResult()
22 {
23 if(4 == xmlHttp.readyState || "complete" == xmlHttp.readyState)
24 {
25 obj2.length=0;
26 obj3.length=0;
27 form1.Wizard1_SchoolAddForm1_District.length=0;
28 obj2.options[obj2.length]=new Option("");
29 obj3.options[obj3.length]=new Option("");
30 var e=xmlHttp.responseText;
31 alert(e);
32 if(e!="未添加")
33 {
34 var a=e.split("*");
35 var arr1=a[0].toString().split(",");
36 var arr2=a[1].toString().split(",");
37 for(var i=0;i<arr1.length;i++)
38 {
39 obj2.options[obj2.length]=new Option(arr1[i]);
40 }
41 for(var j=0;j<arr2.length;j++)
42 {
43 obj3.options[obj3.length]=new Option(arr2[j]);
44 }
45 }
46 }
47 }
48
}
49
50 function CityChange(obj1,obj2,obj3)
51 {
52 if(typeof(ActiveXObject) != "undefined")
53 {
54 if(obj1.selectedIndex==0)
55 {
56 obj2.length=0;
57 obj3.length=0;
58 }
59 else
60 {
61 xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
62 var ReqStr = '<?xml version="1.0"?>';
63 var item = obj1.options[obj1.selectedIndex].text;
64 xmlHttp.open("GET","SettleForm.aspx?city="+item);
65 xmlHttp.send(ReqStr);
66 xmlHttp.onreadystatechange = HandleResult;
67 }
68 }
69 function HandleResult()
70 {
71 if(4 == xmlHttp.readyState || "complete" == xmlHttp.readyState)
72 {
73 obj2.length=0;
74 obj2.options[obj2.length]=new Option("");
75 obj3.length=0;
76 obj3.options[obj3.length]=new Option("");
77 var e=xmlHttp.responseText;
78 if(e!="未添加")
79 {
80 var a=e.split("*");
81 var arr1=a[0].toString().split(",");
82 var arr2=a[1].toString().split(",");
83 for(var i=0;i<arr1.length;i++)
84 {
85 obj2.options[obj2.length]=new Option(arr1[i]);
86 }
87 for(var j=0;j<arr2.length;j++)
88 {
89 obj3.options[obj3.length]=new Option(arr2[j]);
90 }
91 }
92 }
93 }
94
95 }
96
97 function DistrictChange(obj1,obj2)
98 {
99 if(typeof(ActiveXObject) != "undefined")
100 {
101 if(obj1.selectedIndex==0)
102 {
103 obj2.length=0;
104 }
105 else
106 {
107 xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
108 var item = obj1.options[obj1.selectedIndex].text;
109 var ReqStr = '<?xml version="1.0"?>';
110 xmlHttp.open("GET","SettleForm.aspx?district="+item);
111 xmlHttp.send(ReqStr);
112 xmlHttp.onreadystatechange = HandleResult;
113 }
114 }
115 function HandleResult()
116 {
117 if(4 == xmlHttp.readyState || "complete" == xmlHttp.readyState)
118 {
119 obj2.length=0;
120 obj2.options[obj2.length]=new Option("");
121 if(e!="未添加")
122 {
123 var e=xmlHttp.responseText;
124 var arr=e.split(",")
125 for(var i=0;i<arr.length;i++)
126 {
127 obj2.options[obj2.length]=new Option(arr[i]);
128 }
129 }
130 }
131 }
132 }
133
HTML:
<%@ Control Language="C#" AutoEventWireup="true" CodeFile="SchoolAddForm.ascx.cs" Inherits="Contrls_SchoolAddForm" %>
<script language="javascript" type="text/javascript" charset="gb2312" src="../BusinessmanManage/js/JScript.js">
</script>
<table border="0" style="font-size: 100%; width: 60%; height: 415px">
<tr>
<td align="center" colspan="3" style="height: 27px">
学校管理</td>
<td align="center" colspan="1" style="width: 6499px; height: 27px">
</td>
</tr>
<tr>
<td align="right" style="height: 11px; width: 1078px;">
<asp:Label ID="ProvinceLabel" runat="server" AssociatedControlID="Province">所在省(直辖市，自治区):</asp:Label></td>
<td align="right" style="width: 15px; height: 11px;">
</td>
<td style="width: 4767px; height: 11px;">
<asp:DropDownList runat="server" id="Province" onchange="ProvinceChange(form1.Wizard1_SchoolAddForm1_Province,form1.Wizard1_SchoolAddForm1_City,form1.Wizard1_SchoolAddForm1_School)" Height="22px" Width="155px">
<asp:ListItem></asp:ListItem>
<asp:ListItem value="AH">安徽</asp:ListItem>
<asp:ListItem value="BJ">北京</asp:ListItem>
<asp:ListItem value="CQ">重庆</asp:ListItem>
<asp:ListItem value="FJ">福建</asp:ListItem>
<asp:ListItem value="GD">广东</asp:ListItem>
<asp:ListItem value="GS">甘肃</asp:ListItem>
<asp:ListItem value="GX">广西</asp:ListItem>
<asp:ListItem value="GZ">贵州</asp:ListItem>
<asp:ListItem value="HB">河北</asp:ListItem>
<asp:ListItem value="HLJ">黑龙江</asp:ListItem>
<asp:ListItem value="HN">河南</asp:ListItem>
<asp:ListItem value="HN">海南</asp:ListItem>
<asp:ListItem value="HB">湖北</asp:ListItem>
<asp:ListItem value="HN">湖南</asp:ListItem>
<asp:ListItem value="JL">吉林</asp:ListItem>
<asp:ListItem value="JS">江苏</asp:ListItem>
<asp:ListItem value="JX">江西</asp:ListItem>
<asp:ListItem value="LN">辽宁</asp:ListItem>
<asp:ListItem value="NMG">内蒙古</asp:ListItem>
<asp:ListItem value="NX">宁夏</asp:ListItem>
<asp:ListItem value="QH">青海</asp:ListItem>
<asp:ListItem value="SC">四川</asp:ListItem>
<asp:ListItem value="SD">山东</asp:ListItem>
<asp:ListItem value="SH">上海</asp:ListItem>
<asp:ListItem value="SNX">陕西</asp:ListItem>
<asp:ListItem value="SX">山西</asp:ListItem>
<asp:ListItem value="TJ">天津</asp:ListItem>
<asp:ListItem value="XJ">新疆</asp:ListItem>
<asp:ListItem value="XZ">西藏</asp:ListItem>
<asp:ListItem value="YN">云南</asp:ListItem>
<asp:ListItem value="ZZ">浙江</asp:ListItem>
</asp:DropDownList>
<asp:RequiredFieldValidator ID="UserNameRequired" runat="server" ControlToValidate="Province"
ErrorMessage="必须选择所在省。" ToolTip="必须选择所在省。" ValidationGroup="CreateUserWizard1">*</asp:RequiredFieldValidator>
</td>
<td style="width: 6499px; height: 11px">
</td>
</tr>
<tr>
<td align="right" style="height: 1px; width: 1078px;">
<asp:Label ID="CityLabel" runat="server" AssociatedControlID="City">所在城市和地区:</asp:Label>
</td>
<td align="right" style="width: 15px; height: 1px;">
</td>
<td style="width: 4767px; height: 1px;">
&n