Re: Define "flatten database" ?

From: Mark Johnson <>
Date: Sat, 25 Feb 2006 04:12:58 -0800
Message-ID: <>

Jan Hidders <> wrote:

>Mark Johnson wrote:
>> Jan Hidders <> wrote:

>> As for the question, I suspect you had an answer in mind. I don't see
>> that it would matter as the 'splitting' is to be done on the same
>> columns on the same table, at whatever point one decides to do so.

>Really? Note that this is a mathematical theorem about mathematically
>defined objects. Can you supply a mathematical proof?

That you had an answer in mind? Yes. I'll try it, and get back to you.

>> Perhaps I might ask a related question. Do you believe that a table
>> corresponds, but perhaps only weakly, or even inconsistently, to a
>> "relation" as understood in the set theory of the RM, or do you
>> believe it is fair to call the database table a "relation", without
>> much qualification?

>The term "table" is vague and can have different meanings that might
>depend upon the context in which it is used. Without that one cannot
>really answer your question.

It could mean a number of things. But table as a grid, as Codd spoke of, 2-D tables, corresponding to relations. But he also spoke of relations as, relationships, presumeably because the tuples were no longer ordered by a set of ordered domains. In short, in other words, you have the logical presentation, regardless of how it is stored, and then this theoretical notion either of relations or relationships. And it confuses me as to how closely these correspond. Is that the RM in that presentation, or something so different as to be something else? But I'll give it some more thought. Received on Sat Feb 25 2006 - 13:12:58 CET

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