Re: On Formal IS-A definition
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Tue, 04 May 2010 23:34:18 -0300
Message-ID: <4be0d934$0$12449$9a566e8b_at_news.aliant.net>
>
> ..."the entire information content of the database is represented in
> one and only one way. Namely as explicit values in column positions
> (attributes) and rows in relations (tuples)."?
>
> It is obsolete.
>
> Seriously, I think it is aimed at cowboys who try to invent new data
> management systems without studying what relational model is about. It
> is about attributes and tuples because both relational calculus, and
> algebra explicitly refer to relations structured this way. The
> situation is similar to arithmetic where pupils learn how to add/
> multiply numbers represented in a very specific notation. So the
> arithmetic principle would say ..."the entire content of arithmetic is
> represented in one and only one way. Namely as explicit sequences of
> digits in numbers". Presumably arithmetic principle would prevent some
> from reinventing roman numerals:-)
Date: Tue, 04 May 2010 23:34:18 -0300
Message-ID: <4be0d934$0$12449$9a566e8b_at_news.aliant.net>
Tegiri Nenashi wrote:
> On May 3, 5:04 pm, paul c <toledobythe..._at_oohay.ac> wrote:
>
>>... and never bring up, >>say, just what the Information Principle really means.
>
> ..."the entire information content of the database is represented in
> one and only one way. Namely as explicit values in column positions
> (attributes) and rows in relations (tuples)."?
>
> It is obsolete.
>
> Seriously, I think it is aimed at cowboys who try to invent new data
> management systems without studying what relational model is about. It
> is about attributes and tuples because both relational calculus, and
> algebra explicitly refer to relations structured this way. The
> situation is similar to arithmetic where pupils learn how to add/
> multiply numbers represented in a very specific notation. So the
> arithmetic principle would say ..."the entire content of arithmetic is
> represented in one and only one way. Namely as explicit sequences of
> digits in numbers". Presumably arithmetic principle would prevent some
> from reinventing roman numerals:-)
Consider it a restatement of the principle of separation of concerns. Received on Wed May 05 2010 - 04:34:18 CEST