Re: Logical equivalence of simple and complex types under the relational model?
Date: Mon, 29 Nov 2004 16:05:48 -0800
Message-ID: <f2f74$41abb8de$45033832$19131_at_msgid.meganewsservers.com>
Rene de Visser wrote:
> I have read a number of papers that discuss whether complex data types
> should be allowed under the relational model.
>
> What I haven't seen analysed is whether there is actually any logical
> difference (upto renaming/isomorphism) between the resulting models.
languages) it makes no logical difference?
>
> Rene.
>
>
>
If you mean literally a logical difference, then there is. The easiest
way of thinking of logic and databases is to think of the data model as
an interpretation of a language. If the model is composed only of
simple types then the language is first order function free--the kind of
logic that we all learned as undergraduates. If the model allows
complex types then the language is no longer function free--it is more
complex, allowing functions that define the abstract types.
Received on Tue Nov 30 2004 - 01:05:48 CET