On Tue, Jun 30, 2009 at 1:22 PM, Erik Jones<ejones@xxxxxxxxxxxxxx> wrote: >> and if I have a row in table C where c.id is null? A don't know. > > No, it's perfectly clear as 'NULL = NULL' evaluates to false: > > postgres=# select null = null; > ?column? > ---------- > you can test for that with 'is distinct from': select null is distinct from null; -- false select null is distinct from 1; -- true -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
