Re: pro- foreign key propaganda?

From: Brian Selzer <>
Date: Fri, 23 May 2008 05:17:11 -0400
Message-ID: <KXvZj.127$>

"paul c" <toledobysea_at_ac.ooyah> wrote in message news:dorZj.288077$pM4.241855_at_pd7urf1no...
> Brian Selzer wrote:
> ...
>> Who here pretends that an algebraic structure embodies actual 'entities?'
>> Can you cite examples? And by the way, I suggest you read Codd's book.
>> Pages 89-90 describe the Update operator and the justification for it.
>> Also, you might want to look at the article "Extending the Database
>> Relational Model to Capture More Meaning" in TODS 4-4. On page 400,
>> where he is describing the original Relational Model, he writes,
>> All insertions into, updates of, and deletions from base relations
>> are constrained
>> by the following two rules....
>> I could cite other instances, but I think these sufficiently show that
>> you're interpretation of Codd's use of the word 'update' is faulty.
>> ...
> Not to mention any names, BS, but Codd's venture into semantics has
> troubled a lot of the deeper thinkers and prompted many sycophants to
> waste a lot of time for the rest of us. I had a feeling that mentioning
> update might get a mystic or two going, apologies to the others for
> mentioning it. Regarding this, I prefer to think that he was just having
> some fun, hoping to provoke insights in others that he wasn't yet sure of
> (also because I thought he was a nice guy and I respected the clarity and
> resolve he had both before and after his most famous invention). Suit
> yourself if you'd rather spend all your time preferring to think what you
> want. It's hard for me to converse with mystics, especially the ones who
> can't stay on on a single track, mystical or otherwise!

Well, then, let's by all means return to that which prompted me to respond to your post in the first place.

You wrote:


Yes, isn't the choice [of which candidate key is designated as the primary key] what Date calls psychological, ie., part of the desired interpretation. <<

This struck me as odd, since what Date calls psychological refers to what the data means and not how the data is laid out, and the choice of which key is designated to be primary has no bearing whatsoever on what the data means.

I responded:


I don't think the choice has anything to do with the desired or intended interpretation. The information contained within a database is the same regardless of which candidate key is designated to be the primrary key. As far as the logic is concerned, the choice is completely arbitrary. That's not to say that there may not be a sound reason to choose one over another: just that that reason is a matter of implementation, not interpretation. <<

You then responded:


Saying that a choice is arbitrary yet not psychological is the most magical kind of mysticism.

I must say that you are really adept at misinterpretation. You misinterpret Codd's use of the word 'update;' you misinterpret Date's use of the word 'psychological;' and now you've misinterpreted my response altogether. Furthermore, you attributed to me something that I did not say. If I were more of a cynic, I would be led to think you have some underlying agenda, since misdirection is along with projection and obfuscation the bread and butter of most politicians. Instead I am allowing myself to believe that your response can be attributed to your misunderstanding of what consitutes the intended interpretation. Just because the choice may be psychological doesn't mean that it has any effect on the intended interpretation--that is, what the data means. Received on Fri May 23 2008 - 11:17:11 CEST

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