In firebird-support@yahoogroups.com, "Martijn Tonies" wrote:

> > foo == None # allowed, but slower
> > foo is None # preferred
>
> But, what does "none" mean in this case?

None is a special Singleton object which cum
grano salis corresponds to a C NULL pointer.

So of course, the intended (and part of the actual
semantics) doesn't match SQL NULL. (It may be argued
that it is a rather good matched for NULLs created
by JOIN)

kinterbasedb, or generally speaking the Python
DBMS API returns None for SQL NULL. I judge it
less clumsy than a seperate boolean flag.

Regards,
Peter Jacobi