Re: BUG #2178: NOT IN command don't work - Mailing list pgsql-bugs

On Tue, Jan 17, 2006 at 10:00:28PM +0000, Daniel Afonso Heisler wrote:
> When i run the following query, postgreSQL return TRUE.
>  # SELECT true WHERE 1 NOT IN (2,3);
>
> But, when i run the next query, it don't return TRUE
>  # SELECT true WHERE 1 NOT IN (2,NULL,3);

The expression "1 NOT IN (2,NULL,3)" evaluates to NULL because NULL
means "unknown."  This comes up occasionally; see the archives for
past discussion.

http://archives.postgresql.org/pgsql-sql/2005-12/msg00219.php
http://archives.postgresql.org/pgsql-sql/2005-10/msg00227.php

--
Michael Fuhr