> Hi Richard,
> It is the case.
> I have found records with NULL's !
> Exist any docs where I can read more about interpreting of NOT IN ?
There's an item on it in my Postgresql Notes (subqueries and NULLs),
linked to from
http://techdocs.postgresql.org
You can also read more about it in Bruce's book (also available online
from the above URL).
Basically, any good relational database book should have a section of the
meaning of nulls.
- Richard Huxton