Scott Ribe <scott_ribe(at)killerbytes(dot)com> writes:
> Well, actually, it would be:
> a = b or (a = b) is unknown
> But that certainly would more concise.
But
regression=# select (null = null) is unknown;
?column?
----------
t
(1 row)
which I think is not what you wanted.
regards, tom lane