"Andreas Andreakis" <andreas(dot)andreakis(at)googlemail(dot)com> writes:
> So I tried:
> select *
> from A t1 left outer join B t2 on t1.id = t2.id
> where t2.id = null
You need "IS NULL", not "= NULL". See
http://www.postgresql.org/docs/8.1/static/functions-comparison.html
regards, tom lane