On Thu, 20 Mar 2008, Mason Hale wrote: > Hello -- > > I'm getting some unexpected results with a NOT IN query -- this is on 8.2.5. > > This is the query in question: > > prod_2=> select id from feed_download_task where id in (111102466,141701504) > and id not in (select last_feed_download_task_id from subscription);
Is it possible for last_feed_download_task_id be NULL? If so, then then id not in (...) will not ever return true due to the way comparisons with NULLs work -- basically, it can't tell if the id is in the other table because id = NULL is unknown, so it thus can't tell that it's not in the other table either, so you could end up with neither in nor not in returning the row. -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
