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From: sad <sad@bankir.ru>
Organization: IT
To: Markus Bertheau <twanger@bluetwanger.de>
Subject: Re: surrogate key or not?
Date: Wed, 21 Jul 2004 14:30:16 +0400
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On Wednesday 21 July 2004 14:58, Markus Bertheau wrote:

> > 4) Replication:  to identify an object of ANY type (record of any table
> > regardless to datamodel), to store lists of deleted or modified objects
> > (regardless to datamodel)
>
> That sounds like a datamodel on data that belongs to another data model,

that's right, these surr. keys actually belong to a metadata model,
but it is also useful to references of a data model. and they are used this=
=20
way.


> > 5) Making a primary key: if there is no real key at all.
>
> When there's no key at all, there can't be a surrogate key, as I
> understand it. In such cases a generated unique number comes in handy,
> and it's a real primary key and no surrogate key.

...right. in case (5) we construct another datamodel indeed. with an=20
artifichial real key :-)

P.S. r u from Russia ?