Re: Joins with nulls

> I've read that performing joins with tables that have null values in
> some attributes is a dangerous operation, but no example was given. I
> think that this only can happen if you try to join based on the
> attributes that can have two null values, due to the problem of how to
> interpret null values (are two null values equal?). Can this also
> happen in other circumstances?.

Nulls are not values, are a kind of mark.

Anything with nulls is always dangerous.

See the chapter about missing information of:

http://www.amazon.com/exec/obidos/ASIN/0201709287

Saludos
  Alfredo Received on Tue Nov 19 2002 - 15:55:38 CET