Table custom constraints - please help!

On a Table, I am trying to do something like:
"if field1=3 then field2 and field3 must have values"

I have tried the following:
field1=3 and field2 is not null and field3 is not null

It doesn't work because it evaluates the last 2 statements
even if field1 <> 3.

Anyone had any luck with this?

ps Delphi3, NT
Bruce Swart (