Re: Why is "group by" obligatory in SQL?
Date: Fri, 24 Jul 2009 17:08:03 GMT
Message-ID: <TTlam.37974$PH1.35317_at_edtnps82>
Cimode wrote:
...
> To this list I could add a list of hundreds of questions such as:
>
>> What are the fundamental limitations of binary systems one should take into considerations when representing and operating relations.
...
I'd say the very first one is that while we can 'see' or interpret a relation in the mind's eye, the machine representation, whatever form it takes, is by nature (and by definition where an implementation is concerned), idiosyncratic.
>> How to effectively represent disjointness between two sets
Yes, given that representation is very much the basic decision for
implementation. And what 'principles' (maybe axioms is a better word)
could be adopted to interpret disjointness? How practical are the
variious choices? Should an implementation assume disjoint sets that
are eligible subsets of some relation are necessarily contrary assertions?
> ...
.. Received on Fri Jul 24 2009 - 19:08:03 CEST