Re: Why is "group by" obligatory in SQL?
Date: Fri, 24 Jul 2009 09:49:31 -0700 (PDT)
> I suspect that what a 'TRDBMS' is, isn't yet fully known. Lots of open
> questions, here're just a few:
> - Codd espoused logical data independence, yet by assuming some
> relations couldn't be updated in certain ways, he allowed a kind of
> contradiction, or at least a kind of dead-end.
> - there is normalization theory to do with avoiding redundancy, but
> nothing comparable to do with avoiding ambiguity.
> - where is the constraint theory? will normalization turn out to be
> just a small part of this?
> - is the ultimate interface a program that it is in effect a relation?
> - .
> What are the fundamental limitations of binary systems one should take into considerations when representing and operating relations.
> How to effectively represent disjointness between two sets
to name a few... Received on Fri Jul 24 2009 - 18:49:31 CEST