I'd probably populate the first drop down as you would normally. (Gawd, let me see if I remember by Classic ASP)
Something like:
<%
Response.Write("<SELECT id='ddParent' onchange='populateSecondDropDown();'>")
Response.Write("<OPTION>" & Row("system_id") & "'</OPTION>")
Response.Write("</SELECT>")
%>
Then I would write the list of the child items to some sort of JavaScript structure that associated the parent with the child:
(Note, this is pseudo-code JavaScript. No guarantees are made here!)
<SCRIPT>
var childItems = <%
'Loop through the RecordSet that contains child and parent records
%>;
</SCRIPT>
so that the result would look something like this in JSON format:
var childItems = {"System AAA": {"12345", "23333"}};
Finally, I'd write the function associated with the change in the parent dropdown
populateSecondDropDown()
.
<SCRIPT>
function populateSecondDropDown(){
var dropDown = document.getElementById("ddParent");
dropDown.innerHtml = "";
}
</SCRIPT>