这叫连动，给你两个例子，如果你要三级连动的例子我也可以给你的！
数据库版：
<%@ Language=VBScript %>
<%Option Explicit%>
<html>
<head>
<title>List</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<%
dim conn
dim rs
dim sql
dim count
dim rs1
dim sql1
set conn = server.CreateObject ("adodb.connection")
conn.Open "test","sa",""
sql = "select * from district order by locationid asc"
set rs = conn.execute(sql)
%>
<script language = "JavaScript">
var onecount;
onecount=0;
subcat = new Array();
<%
count = 0
do while not rs.eof
%>
subcat[<%=count%>] = new Array("<%= trim(rs("districtname"))%>","<%= trim(rs("locationid"))%>","<%= trim(rs("districtid"))%>");
<%
count = count + 1
rs.movenext
loop
rs.close
set rs=nothing
%>
onecount=<%=count%>;
function changelocation(locationid)
{
document.myform.smalllocation.length = 0;
var locationid=locationid;
var i;
document.myform.smalllocation.options[0] = new Option('====所有地区====','');
for (i=0;i < onecount; i++)
{
if (subcat[i][1] == locationid)
{
document.myform.smalllocation.options[document.myform.smalllocation.length] = new Option(subcat[i][0], subcat[i][2]);
}
}
}
</script>
</head>
<body>
<form name="myform" method="post">
<select name="biglocation" onChange="changelocation(document.myform.biglocation.options[document.myform.biglocation.selectedIndex].value)">
<%
sql1 = "select * from location order by locationname asc"
set rs1 = conn.Execute (sql1)
do while not rs1.eof
%>
<option value="<%=trim(rs1("locationid"))%>"><%=trim(rs1("locationname"))%></option>
<%
rs1.movenext
loop
rs1.close
set rs1 = nothing
conn.Close
set conn = nothing
%>
</select>
<select name="smalllocation">
<option selected value="">==所有地区==</option>
</select>
</form>
<script LANGUAGE="javascript">
changelocation(document.myform.biglocation.options[document.myform.biglocation.selectedIndex].value);
</script>
</body>
</html>
数据库：
create table location
(
locationid char(2) not null primary key,
locationname char(50) not null
)
create table district
(
districtid char(3) not null primary key,
districtname char(50) not null,
locationid char(2) not null
)
html版
<html>
<head>
<title>List</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<script LANGUAGE="javascript">
<!--
var onecount;
onecount=0;
subcat = new Array();
subcat[0] = new Array("徐汇区","01","001");
subcat[1] = new Array("嘉定区","01","002");
subcat[2] = new Array("黄浦区","01","003");
subcat[3] = new Array("南昌市","02","004");
subcat[4] = new Array("九江市","02","005");
subcat[5] = new Array("上饶市","02","006");
onecount=6;
function changelocation(locationid)
{
document.myform.smalllocation.length = 0;
var locationid=locationid;
var i;
document.myform.smalllocation.options[0] = new Option('====所有地区====','');
for (i=0;i < onecount; i++)
{
if (subcat[i][1] == locationid)
{
document.myform.smalllocation.options[document.myform.smalllocation.length] = new Option(subcat[i][0], subcat[i][2]);
}
}
}
//-->
</script>
</head>
<body>
<form name="myform" method="post">
<select name="biglocation" onChange="changelocation(document.myform.biglocation.options[document.myform.biglocation.selectedIndex].value)">
<option value="01" selected>上海</option>
<option value="02">江西</option>
</select>
<select name="smalllocation">
<option selected value="">==所有地区==</option>
</select>
</form>
<script LANGUAGE="javascript">
<!--
changelocation(document.myform.biglocation.options[document.myform.biglocation.selectedIndex].value);
//-->
</script>
</body>
</html>
