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Re: database design method

From: Jan Hidders <hidders_at_hcoss.uia.ac.be>
Date: 19 Nov 2002 10:35:13 +0100
Message-ID: <3dda05d1$1@news.uia.ac.be>


In article <3DD8CD14.4D3657A3_at_atbusiness.com>, Lauri Pietarinen <lauri.pietarinen_at_atbusiness.com> wrote:
>
>Jan:
>
>first you say that "you may run out of them [integers]"
>
>then the problem is that different id's get assigned.
>
>???

Yes, both are a problem. Why do you think these remarks are not compatible?

>We must be assuming that the database is changing
>all the time anyway, so if we want the class_id to mean
>something, we would have to have a separate
>table to describe the meaning of each class.

No, no, they already have a meaning; the represent a set of customers as difened by the Bought table.

>Anyway: how do abstract identifiers help? Now
>we have to assign the same abstract indentifier
>to each class - same problem I suppose?

The user doesn't assign anything. That's the whole point. And since the user cannot see the identifiers he or she can also not see whether the database is now using other surrogate identifers or not.

I'm a bit time pressed at the moment, so if you don't mind I will try to explain it a bit more fully another time.

Received on Tue Nov 19 2002 - 03:35:13 CST

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