Dynamic WHERE clause?

["Adem M. Hamidovic" <hamidoam@TUNS.CA>]

Hi all. Thanks for helping out with my input problem - that part works
fine now :)  The other problem I'm wrestling with at the moment is how to
set a WHERE clause based on user input. Specifically, if the user enters
one value for a variable, use one WHERE clause, else use a different
WHERE clause. I tried putting an IF statement following the FROM and it
complained. Is there any way to do this other than having two different
SELECT sections?

As always, I'd appreciate any help :)

Adem