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Re: What databases have taught me

From: Frans Bouma <perseus.usenetNOSPAM_at_xs4all.nl>
Date: 28 Jun 2006 09:41:26 GMT
Message-Id: <xn0eo0f8s7nto6003@news.xs4all.nl>


mAsterdam wrote:

> Frans Bouma wrote:
> [snip]
>
> > Funny thing is that if you give 3 randomly chosen database
> > architects (or whatever the f... some people want to call these
> > people) the task to develop the RDM for a big hospital (so you end
> > up with at least 700 or so tables), you will definitely get 3
> > completely different models.
>
> Is this from experience - did you see 3 actual models for
> a big hospital? Did you try to find out what was same,
> similar and different? I speculate that it is speculation.

        I have, actually. All 3 had over 1000 tables. Not for the same hospital, but all were databases for the information systems for big hospitals. It struck me that they were so different. Of course they all define 'patient' but it was kind of odd that they ended up with such different models. And yet, when you looked at them they all made sense.

> It does not match my experience. I did some admittedly
> shallow comparisons of different data models in operation
> for different organizations in the same businesses
> (not hospitals). The similarities were striking,
> noted differences were accounted for.
> I think this is because when you are in the same
> business, you have to deal with the same
> facts. If you don't you are in a niche.

        Then our experiences differ indeed. :)

        My example was more to illustrate that if you talk about something like 'RM' the end result of the analysis phases might be a RDM, and it also might be following all the rules defined for RM, but semantically, does it make sense, is it 'correct' when you project it on reality? That's something that's unclear, which is the same with OOAD and which was IMHO the reason why it was more or less classified as not useful by some, while RM and OOAD are actually in the same boat: the end result can be tested technically if they obey the rules of RM resp. OOAD, but if they are 'correct' with respect to reality is not clear in both situations as in: not for 100% certain. (otherwise no software project would ever fail ;))

                FB

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Received on Wed Jun 28 2006 - 04:41:26 CDT

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