Re: Guessing?

From: paul c <toledobysea_at_ac.ooyah>
Date: Tue, 27 May 2008 13:59:38 GMT
Message-ID: <etU_j.167881$rd2.59570_at_pd7urf3no>

Brian Selzer wrote:
> "Bob Badour" <> wrote in message
> news:483ac46d$0$4069$

>> paul c wrote:
>>> Bob Badour wrote:
>>> ...
>>>> ... (Not that I like anthropomorphizing dbmses.)
>>> Right, saying the dbms 'knows' something invites talk of it being able to 
>>> 'guess' and other mysticisms.  For want of a better word, for now I'll 
>>> try to remember to quote it.
>> With POOD, any tuple satisfies the predicate of at most one relation in 
>> the dbms. Thus, with POOD, the dbms can calculate a unique relation to 
>> which to apply any insert, update or delete with the goal of avoiding 
>> anomalous behaviour.

> This just does not make sense. Suppose that a Vendor can also be a Customer
> since they're both Companies, and suppose that Company 'Philco' usually
> supplies 'RG6 connectors,' but occasionally buys them. So then if you have
> two relations,
> VendorParts {Company, Part},
> CustomerParts {Company, Part},
> that enumerate the parts that a company supplies and the parts that a
> company buys respectively,
> the tuple, {Company:'Philco', Part:'RG6 connector'}, can obviously appear in
> both relations, so I don't buy the notion 'any tuple satisfies the predicate
> of at most one relation.'
> ...

Isn't this a straw man too? (arguing against POOD with an example that doesn't follow POOD.) Received on Tue May 27 2008 - 15:59:38 CEST

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