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Re: Multi Valued Interface Models?

From: paul c <>
Date: Sun, 12 Feb 2006 02:06:27 GMT
Message-ID: <DKwHf.376101$tl.41929@pd7tw3no>

David Cressey wrote:
> "dawn" <> wrote in message

>>OK, no, my argument is that it is not possible to employ the RM as the
>>data model for a general user interface.  Surely you can use the RM to
>>persist data that makes its way to a UI, but you cannot use the RM as
>>the data model of the interface to the user.  You need an understanding
>>of what a data model is (e.g. from my blog entry The Naked Model).
>>Then separate yourself from thinking about the data model for the
>>database (that is the model of the interface to the database) and focus
>>on the data model of the interface to the user.  It simply is not
>>possible for the RM to be the data model for that interface.

> Not possible, or not useful?
> It seems to me that for every unnormalized schema of relations, there exists
> an normalized schema that can convey the same information. ...

Many, I'd guess.

> I think that's what Codd said.
> It seems to me that for any possible set of information requirments, there
> exists a (possibly unnormalized) schema of relations that can convey that
> information. I know you claimed to the contrary regarding a model to back a
> web page, but I have yet to be convinced of that.
> If you put the above two together, it seems one has to conclude that there
> does not exist a set of information requirements that cannot be conveyed by
> a normalized schema of relations. Whether that's the right way to go or not
> is an entirely different matter.
> ...

Somebody else alluded to this recently, if I'm reading it right. I think it might be important, in the same sense that Codd saw it as important to provide an intuitive interface in the form of 'tables'.

There is so little in IT that is 'right' and I can't say why I think this the above is right, but the appeal seems innate to me. No fan of the elaborate X-windows implementations, but I think they got one basic right - the display or screen is a 'server'. For me, this just cries out for the RM, albeit one that doesn't insist on single-table closure.

Since an RM relation (I think Codd called it a relationship) is actually two sets, not one as people often describe it, it doesn't seem a big leap to find an elegant way to handle the notational stuff that people find helpful even if I'm not smart enough to see one. I wonder if another aspect isn't missing - that of two db's that are mergeable in some formal way.

p Received on Sat Feb 11 2006 - 20:06:27 CST

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