Re: pro- foreign key propaganda?

"paul c" <toledobysea_at_ac.ooyah> wrote in message news:x9CYj.281607$pM4.252830_at_pd7urf1no...
> David Cressey wrote:
> ...
>> Absolutely. In the previous comments in this thread, the term "candidate
>> key" was used.
>> You can shorten that to simply, "key", if you like. No problem. The
>> word
>> "candidate" was introduced into the terminology with the idea that the
>> primary key would be selected among the candidate keys. What I think
>> I've
>> learned in c.d.t. in years gone by is that the selection of one candidate
>> key to be the primary key is not inherent in Relational modeling. IIRC,
>> I
>> learned it from Bob's writings.
>> ...
>
>
> Yes, isn't the choice what Date calls psychological, ie., part of the
> desired interpretation.

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.

>
> ...
>> I don't know "aref". That's a new one on me.
>> ...
>
>
> Oh, I should have said "a href".
>
>
>> But don't get me started on HTML. I think that it was a wonderful thing
>> for
>> a physicist to come up with a way of propagating information over the
>> internet without being blocked by format incompatibilities. But I also
>> think that HTML was the ultimate perpetration of an uncontrolled graph of
>> "hrefs" and pages. It has all the problems of a graph DBMS, and then
>> some.
>
>
> Okay, don't get me started on mysticism either!
Received on Wed May 21 2008 - 13:48:08 CEST