Nando,

> NULL = 1 null
> NULL = NULL null
> NULL <> 1 null
> NULL <> NULL null

I think you're absolutely right. Sorry for saying they were false - I just
did a simple select where I checked the one thing I was somewhat uncertain
about:

SELECT *
FROM A
WHERE A.FIELD1 <> A.FIELD2
AND A.PK = :PK

on a record I new contained null values for FIELD1 and FIELD2. When I
discovered that it didn't return any result, I concluded that FIELD1 was
neither equal nor different from FIELD2 and that the comparisons evaluated
to false. But of course they are null, we don't know.

I honestly don't know how this would behave in a stored procedure or
trigger with an if... else... statement.

Set