Stephan Szabo <sszabo@xxxxxxxxxxxxxxxxxxxxx> writes: > On Thu, 17 Aug 2006, Alexander Farber wrote: >> But the negative one returns nothing: >> >> phpbb=> select user_id, username from phpbb_users >> phpbb-> where user_id not in (select ban_userid from phpbb_banlist); >> user_id | username >> ---------+---------- >> (0 rows) > Sadly, these two look like they would give you all the users rows, but > they don't because of the NULL ban_userid. When the subselect returns > NULL for at least one row, you fall into this sort of case. Seems like the NULLs-in-NOT-IN thing ought to be in our FAQ list. It certainly bites newbies often enough :-( regards, tom lane
