asp javascript 二级联动select 产品大类,小类

<select name="BigClassName" onChange="changelocation(document.myform.BigClassName.options[document.myform.BigClassName.selectedIndex].value)" size="1">
<%
dim rsBigClass
set rsBigClass=server.CreateObject("adodb.recordset")
rsBigClass.open "Select * From "&BigClass,conn,1,1
if rsBigClass.bof and rsBigClass.bof then
response.write "<option>请先添加产品大类</option>"
else
response.write "<option selected value='"& rsBigClass("BigClass_Name") & "'>" & rsBigClass("BigClass_Name") & "</option>"
dim selclass
selclass=rsBigClass("BigClass_Name")
rsBigClass.movenext
do while not rsBigClass.eof
response.write "<option value='"& rsBigClass("BigClass_Name") & "'>" & rsBigClass("BigClass_Name") & "</option>"
rsBigClass.movenext
loop
end if
rsBigClass.close
set rsBigClass=nothing
%>
</select>
<select name="SmallClassName">
<option value="" selected>不指定小类</option>
<%
dim rsSmallClass
set rsSmallClass=server.CreateObject("adodb.recordset")
rsSmallClass.open "Select * From "& SmallClass &" where BigClass_Name='"&selclass&"'",conn,1,1
if rsSmallClass.bof and rsSmallClass.bof then
response.write "<option>请先添加产品小类</option>"
else
do while not rsSmallClass.eof
response.write "<option value='"& rsSmallClass("SmallClass_Name") & "'>" & rsSmallClass("SmallClass_Name") & "</option>"
rsSmallClass.movenext
loop
end if
rsSmallClass.close
set rsSmallClass=nothing
%>
</select>

<%

dim rs
dim sql
dim count
set rs=server.createobject("adodb.recordset")
sql = "select * from "&SmallClass&" order by SmallClass_Id asc"
rs.open sql,conn,1,1
%>
<script language = "JavaScript">
var onecount;
subcat = new Array();
<%
count = 0
do while not rs.eof
%>
subcat[<%=count%>] = new Array("<%= rs("SmallClass_Name")%>","<%= rs("BigClass_Name")%>","<%= rs("SmallClass_Name")%>");
<%
count = count + 1
rs.movenext
loop
rs.close
%>
onecount=<%=count%>;

function changelocation(locationid)
{
document.myform.SmallClassName.length = 1;
var locationid=locationid;
var i;
for (i=0;i < onecount; i++)
{
if (subcat[i][1] == locationid)
{
document.myform.SmallClassName.options[document.myform.SmallClassName.length] = new Option(subcat[i][0], subcat[i][2]);
}
}
}
</script>