Stored procs: detecting when SELECT returns no records

I am an SQL novice trying to teach myself Informix on AIX using nothing more than the Informix manuals. While the books seem pretty good, stored procedures seem to be only BARELY documented. Much is left to the imagination and trial/error. What is the proper way, in a stored procedure, to detect when a single-row SELECT doesn't find a row? The only mechanism I saw in the manuals was the ON EXCEPTION statement. However, when I tried it, I observed no exception. What happened instead was that the variable I was selecting into was set to NULL. Is that the only indication that a SELECT didn't find a record? Seems ambiguous unless the column in question has a not-null constraint. Basically, here's the *pseudo* code for what I'm trying to do in this particular procedure. If someone would be kind enough to suggest the proper way to accomplish this in an Informix stored procedure, I'll be very grateful: SELECT quantity FROM history WHERE history.sku = sku AND history.date = date; IF no record found INSERT new record into history table ELSE UPDATE quantity in existing record in history table Andrew Ernest andrew@infi.net