--- In firebird-support@yahoogroups.com, Jonathan Neve <jonathan@m...>
wrote:

> >>IMHO, this unique feature could nearly be considered a bug...
> >>
> >>
> >
> > In SQL standard? ;)
> >
> >
> Absolutely! A bug in that it defines a useless distinction that would
> forever be a nuisance for every database developer! :-)

Useless? NULL shows 'untouched', 'not any value assigned' in rows
and 'row does'nt' exists' in outer joins.
BTW, Delphi recognizes NULL too (TField.IsNull). And if you prefer
to recognize it in visualisation, you can set TField.DefaultExpression.

Best regards,
Alexander.