<label><select name="b_classid" >
<%
set rs=server.createobject("adodb.recordset")
rs.open "select * from big_class",conn,1,3
do while not rs.eof%>
<option value="<%=rs("id")%>"><%=rs("b_class")%></option>
<%rs.movenext
loop
rs.close%></select>
</label>
<label><select name="s_classid" >


<%
id=Request.QueryString("id")

set rst=server.createobject("adodb.recordset")
sql= "select * From s_class Where b_classid in("&Request.QueryString("id")&")"
rst.open sql,conn,3,3

do while not rst.eof%>
<option value="<%=rst("id")%>"><%=rst("b_class")%></option>
<%rst.movenext
loop
rst.close%></select>
两个select这么用iframe连起来啊????