Re: In an RDBMS, what does "Data" mean?

From: mAsterdam <>
Date: Sun, 13 Jun 2004 18:22:07 +0200
Message-ID: <40cc7f2b$0$34762$>

Dawn M. Wolthuis wrote:
"x" wrote:

>>>So if I put my data into an MV database I can access it as if it were in
>>>an RDBMS. However, the converse is not true.
>>So all data in a MV database can be represented in relational model,
>>but not all data in a RDBMS can be represented in MV model :-)
>>Which one is more expressive ? :-)

> Easy question --
> if each model can provide a solution for a particular area so that we have
> both an MV and a SQL-DBMS solution and
> if we can look at the MV model as relational when we choose to do so (which
> is usually for the purpose of using SQL against it)
> but we cannot take the relational model and view the MV model from it
> Then clearly the more expressive language is ... NOT the one that loses the
> ability to view the data in some other way, right? --dawn

So now we have language R and language M.

R 'loses the ability to view the data' from within M and that would somehow mean M is *more* expressive? The only way I could make sense out of that is if the (appearant) excess expressions in R could *not* be relevant to a solution.

Do you have an indication as to what those excess expressions are? Which statements can you make in R but not in M - IOW of which data does R lose 'the abitlity to view the data in some other way'?

x's question may be easy, your answer sure isn't. Received on Sun Jun 13 2004 - 18:22:07 CEST

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