How to make a follow up number

I am trying to make the following work in ASP in combination with SQL

A00001, A00002, ..... A99999, B00001, B00002,
.....B99999, C00001

It has to be an unique number....

I have come this far...

<!-- #Include FILE="../connections/conn_????.asp"--><%
Set rs = server.CreateObject ("ADODB.recordset")

SQL = "Select max(volgnummer)as volgnummer from Formteller"
set rs = conn.Execute(SQL)
volgnummer = rs("volgnummer")+ 1

SQL = "UPDATE Formteller SET volgnummer=" & volgnummer
set rs = conn.Execute(SQL)



Can someone please help me
Sorry for the bad English


Edited by sierra

The easiest solution is to set the 'volgnummer' field to an autonumber type. This will generate a new and unique number for each new record entered into the database.

Blair