如何制作关联的下拉菜单？

<form name=f1 method="post">

<%

opendb objconn, "xxxx"

set rsclass = objconn.execute("select * from class order by fldclass")

if rsclass.eof then

response.write "噢,没有记录!<br>"

else

response.write "<select name=""class"" style=""font-size: 9pt"" size=10"

" onchange=""classselected(this);"" >"

sjavascript = "function classselected(elem){" &_

vbcrlf

"for (var i = document.f1.sort.options.length; i >= 0; i--){" 

"document.f1.sort.options[i] = null;" 

vbcrlf

do until rsclass.eof

if slastclass <> rsclass("fldclass") then

slastclass = rsclass("fldclass")

response.write "<option value=" & rsclass("fldid") & ">" & slastclass & "</option>"

sjavascript = sjavascript & "}" 

"if (elem.options[elem.selectedindex].value=="

rsclass("fldid") & "){"

end if

sjavascript = sjavascript

"document.f1.sort.options[document."

"f1.sort.options.length] = new option('"

rsclass("fldsort") & "','" & rsclass("fldid") & "');"

vbcrlf

rsclass.movenext

loop

 

response.write "</select>"

response.write "<select name=""sort"" style=""font-size: 9pt"" size=10>"

response.write "<option>请选择</option>"

response.write "</select>"

　

sjavascript = sjavascript  & "}"  & "}"

 

response.write "<scr" & "ipt language=""javascript"">"

response.write sjavascript  & "</scr" & "ipt>"

 

end if

rsclass.close

set rsclass = nothing

%>

</form>