Unique combo box sample
Here is the code for this Example <%@ Language=VBScript %>
<HTML>
<HEAD>
<META NAME="GENERATOR" Content="Microsoft Visual Studio 6.0">
</HEAD>
<title>Unique combo box sample</title>
<BODY>
<!-- Author: Adrian Forbes -->
<%
set objRS = createobject("ADODB.Recordset")
objRS.Open "select strParent from Parent", strconn
set objDic = CreateObject("Scripting.Dictionary")
while not objRS.EOF
sString = cStr(objRS("strParent"))
if not objdic.Exists (sString) then
objDic.Add sString, sString
end if
objRS.MoveNext
wend
objRS.Close
set objRS.ActiveConnection = nothing
set objRS = nothing
%>
<form name=frmTest action="TwoComboDatabase.asp" method=POST>
<p>
<select name=cboPrimary size=1>
<%
aResults = objDic.Items
for i = 0 to objDic.Count - 1%>
<option><%=aResults(i)%>
<%next
objDic.RemoveAll
set objDic = nothing
%>
</select>
</p>
</form>
</BODY>
</HTML> | 
ASP Code 
Building a Web Form in ASP.NET
