Re: Guessing?

From: Brian Selzer <brian_at_selzer-software.com>
Date: Tue, 27 May 2008 16:08:35 -0400
Message-ID: <7TZ_j.2509$N87.703_at_nlpi068.nbdc.sbc.com>

"paul c" <toledobysea_at_ac.ooyah> wrote in message news:etU_j.167881$rd2.59570_at_pd7urf3no...

> Brian Selzer wrote:

>> "Bob Badour" <bbadour_at_pei.sympatico.ca> wrote in message
>> news:483ac46d$0$4069$9a566e8b_at_news.aliant.net...

>>> 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.)

I think it does follow POOD, but I think Badour's overstrict interpretation of POOD is flawed. Received on Tue May 27 2008 - 22:08:35 CEST