Dynamic Triple Linked Dropdowns

<SCRIPT LANGUAGE="JavaScript">
<!-- 
function clearcombo(elem){
 var i;
 for (i = elem.options.length; i >= 0; i--) elem.options[i] = null;
 elem.selectedIndex = -1;
}
function populatecombo2(elem, index){
 if (array1.length >= index){
  if (array1[index]){
   for (var i = 0; i < array1[index].length; i= i + 2){
	elem.options[elem.options.length] = new Option(array1[index][i + 1], array1[index][i]);
   }
  }
  else{
   elem.options[elem.options.length] = new Option("[none available]", 0);
  }
 }
 else{
  elem.options[elem.options.length] = new Option("[none available]", 0);
 }
}
function populatecombo3(elem, index){
 if (array2.length >= index){
  if (array2[index]){
   for (var i = 0; i < array2[index].length; i= i + 2){
	elem.options[elem.options.length] = new Option(array2[index][i + 1], array2[index][i]);
   }
  }
  else{
   elem.options[elem.options.length] = new Option("[none available]", 0);
  }
 }
 else{
  elem.options[elem.options.length] = new Option("[none available]", 0);
 }
}
function clickcombo(nWhich,elem1,elem2,elem3){
 if (nWhich == 1){
  clearcombo(elem2);
  clearcombo(elem3);
  populatecombo2(elem2, elem1[elem1.selectedIndex].value);
 }
 if (nWhich == 2){
  clearcombo(elem3);
  populatecombo3(elem3, elem2[elem2.selectedIndex].value);
 }
 return true;
}
// -->
</script>

<%
' this section of code is self-contained and suitable to be moved to an include file
Function TripleLinkedList(oCon, sQuery, sFormFieldName, nSize, sDBField1, sDBField2, sDBField3, sDBFieldResult)
 ' this is a general-purpose routine that implements triple-linked
 ' listboxes. here is the drill
 Dim sTemp  ' general-purpose temp variable
 Dim sScript  ' bucket for holding the script structure
 Dim sSelect  ' bucket for the <SELECT> statement
 Dim sArray1  ' bucket to store the DBField2 array
 Dim nField1  ' counter for the primary array
 Dim sArray2  ' bucket to store the DBField3 array
 Dim nField2  ' counter for the secondary array
 Dim rs   ' recordset
 Dim sLastVal1 ' comparison string to test for record changes
 Dim sLastVal2 ' comparison string to test for record changes
 On Error Resume Next
 If Not IsObject(oCon) Then
  sScript = "error processing triplelist -- need a connection object."
 ElseIf oCon.State <> 1 Then
  If Err.number <> 0 Then
   sScript = "error processing triplelist -- invalid connection object."
  Else
   sScript = "error processing triplelist -- connection is not open."
  End If
 Else
  Set rs = oCon.Execute(sQuery)
  If Err.number <> 0 Then
   sScript = "error processing query. Error " & Hex(Err.number) & ": " & Err.Description
  ElseIf rs.EOF Then
   sScript = "no records found -- seems wrong"
  Else
   On Error Goto 0 
   sScript = "<SCR" & "IPT LANGUAGE=""JavaScript"">" & vbCrlf
   sScript = sScript & "var array1 = new Array();" & vbCrlf
   sScript = sScript & "var array2 = new Array();" & vbCrlf
   sSelect = "<SELECT NAME=""" & sFormFieldName & "1"" SIZE=""" & nSize & _
	""" ONCHANGE=""return(clickcombo(1,document.forms[0]." & _
	sFormFieldName & "1,document.forms[0]." & sFormFieldName & _
	"2,document.forms[0]." & sFormFieldName & "3));""><OPTION>Select a value</OPTION>" & vbCrlf
   sLastVal1 = "empty" ' set up a default test value...
	  Do Until rs.EOF
		  If rs(sDBField1) <> sLastVal1 Then
	 If Right(sArray1, 3) = "," & vbCrlf Then
	  ' pull off any trailing commas
	  sArray1 = Left(sArray1, Len(sArray1) - 3)
	 End If
	 If Len(sArray1) > 0 Then
	  sArray1 = sArray1 & ");" & vbCrlf
	 End If
	 ' pick up new information for this row...
	 nField1 = nField1 + 1
	 sLastVal1 = rs(sDBField1)
	 ' write the new contents of field 1 to the select statement
	 sSelect = sSelect & "<OPTION VALUE=" & nField1 & ">" & sLastVal1 & "</OPTION>"
	 ' write a new entry in array1 for the field 2 values...
	 sArray1 = sArray1 & "array1[" & nField1 & "] = new Array(" & vbCrlf
	 ' and reset the test values for field 2
	 nField2 = 0
	 sLastVal2 = "empty"
	End If
	If sLastVal2 <> rs(sDBField2) Then
	 If Right(sArray2, 3) = "," & vbCrlf Then
	  ' pull off any trailing commas
	  sArray2 = Left(sArray2, Len(sArray2) - 3)
	 End If
	 If Len(sArray2) > 0 Then
	  sArray2 = sArray2 & ");" & vbCrlf
	 End If
	 ' pick up new information for this row...
	 sLastVal2 = rs(sDBField2)
	 nField2 = nField2 + 1
	 ' write a new entry in array1 containing this set of field 2 values...
	 sArray1 = sArray1 & "	" & 1000 * nField1 + nField2 & ",""" & sLastVal2 & """," & vbCrlf
	 ' write a new entry in array2 for this set of field 3 values...
	 sArray2 = sArray2 & "// values for " & sLastVal2 & vbCrlf
	 sArray2 = sArray2 & "array2[" & 1000 * nField1 + nField2 & "] = new Array(" & vbCrlf
	End If
	' write the field3 values to the field2 array...
	sArray2 = sArray2 & "	" & rs(sDBFieldResult) & ",""" & rs(sDBField3) & """," & vbCrlf
	rs.MoveNext ' move on to the next record...
   Loop
   ' if these arrays weren't previously closed out, then close them now
   If Right(sArray2, 3) = "," & vbCrlf Then
	' pull off any trailing commas
	sArray2 = Left(sArray2, Len(sArray2) - 3)
   End If
   If Len(sArray2) > 0 Then
	sArray2 = sArray2 & ");" & vbCrlf
   End If
   ' if these arrays weren't previously closed out, then close them now
   If Right(sArray1, 3) = "," & vbCrlf Then
	' pull off any trailing commas
	sArray1 = Left(sArray1, Len(sArray1) - 3)
   End If
   If Len(sArray1) > 0 Then
	sArray1 = sArray1 & ");" & vbCrlf
   End If
   ' close out the listbox/combobox and add the second and third listbox/combobox entries...
   sSelect = sSelect & "</SELECT>" & vbCrlf
   sSelect = sSelect & "<SELECT NAME=""" & sFormFieldName & "2"" SIZE=""" & nSize & _
	""" ONCHANGE=""return(clickcombo(2,document.forms[0]." & sFormFieldName & _
	"1,document.forms[0]." & sFormFieldName & "2,document.forms[0]." & _
	sFormFieldName & "3));""><OPTION>Select a value</OPTION></SELECT>" & vbCrlf
   sSelect = sSelect & "<SELECT NAME=""" & sFormFieldName & "3"" SIZE=""" & nSize & _
	"""><OPTION>Select a value</OPTION></SELECT>" & vbCrlf
   ' finally clean up the script and write the whole thing out as a block
   sScript = sSelect & vbCrlf & _
	sScript & vbCrlf & _
	sArray1 & vbCrlf & _
	sArray2 & vbCrlf & _
	"</SCR" & "IPT>" & vbCrlf
  ' -----------------------------------------------------------------
  End If
  ' close and free the recordset
  rs.Close
  Set rs = Nothing
 End If
 ' and get the fleep outta here
 TripleLinkedList = sScript
End Function
%>

<% 
Dim Conn
Dim sQuery
Set Conn = Server.CreateObject("ADODB.Connection")
conn.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & Server.mappath("yourdbname.mdb")
conn.Open ' connect to the database
' -----------------------------------------------
' then set up a query
' -----------------------------------------------
sQuery = "SELECT DISTINCT * from tablename Order By columnA, columnB " ' << insert your own sql here
%>
<FORM id=form1 name=form1>
<CENTER>
<%
Response.Write TripleLinkedList(Conn, sQuery, "listboxname", 1, "dbfieldname-for-1st-listbox", "dbfieldname-for-2nd-listbox", "dbfieldname-for-3rd-listbox", "name-of-the-result-from-sql")
Conn.Close
Set Conn = Nothing
%>
<P>
</FORM>

	  If rs(sDBField1) <> sLastVal1 Then
	 If Right(sArray1, 3) = "," & vbCrlf Then
	  ' pull off any trailing commas
	  sArray1 = Left(sArray1, Len(sArray1) - 3)
	 End If
	 If Len(sArray1) > 0 Then
	  sArray1 = sArray1 & ");" & vbCrlf

nField2 = nField2 + 1
			 		' write a new entry in array1 containing this set of field 2 values...
			 		sArray1 = sArray1 & "	" & 1000 * nField1 + nField2 & ",""" & sLastVal2 & """," & vbCrlf
	 				' write a new entry in array2 for this set of field 3 values...
	 				sArray2 = sArray2 & "// values for " & sLastVal2 & vbCrlf
	 				sArray2 = sArray2 & "array2[" & 1000 * nField1 + nField2 & "] = new Array(" & vbCrlf
				End If

If rs(sDBField1) <> sLastVal1 Then

 sLastVal1 = "empty" ' set up a default test value...
	  Do Until rs.EOF
		  If rs(sDBField1) <> sLastVal1 Then
	 If Right(sArray1, 3) = "," & vbCrlf Then
	  ' pull off any trailing commas
	  sArray1 = Left(sArray1, Len(sArray1) - 3)
	 End If 

sQuery = "SELECT DISTINCT * from tablename Order By columnA, columnB " ' << insert your own sql here

sQuery = "select * from tbl_continents order by continent"

'--> select values for country, drop down 2
'--> check if continent has a value, if it has, use the value in your sql

if Len(request.form("continent")) > 0 then
	sQuery = "select * from tbl_countries order by country where continent_ID = " & request.form("continent")
else
	sQuery = "select * from tbl_countries order by country"
end if


'--> select values for place, drop down 3
'--> check if country has a value, if it has, use the value in your sql

if Len(request.form("country")) > 0 then
	sQuery = "select * from tbl_place order by place_name where country_ID = " & request.form("country")
else
	sQuery = "select * from tbl_place order by PlaceName"
end if

function populatecombo2(elem, index){
 if (array1.length >= index){
  if (array1[index]){


	elem.options[elem.options.length] = new Option('select', 'select');


   for (var i = 0; i < array1[index].length; i= i + 2){
	elem.options[elem.options.length] = new Option(array1[index][i + 1], array1[index][i]);
   }
  }
//snip