John Scott <jmscott(at)yahoo(dot)com> writes:
> select count(*) from A where b = null; /* Returns 1, ok */
> select count(*) from A where b != null; /* Returns 0 ... not ok! */
Uh ... there have been several threads about this just in the past
couple days. See for example
http://www.ca.postgresql.org/mhonarc/pgsql-sql/2001-06/msg00102.html
and followups.
regards, tom lane