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Re: No exceptions?

From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Thu, 29 Jun 2006 21:41:55 GMT
Message-ID: <DOXog.3864$pu3.91530@ursa-nb00s0.nbnet.nb.ca>


paul c wrote:

> J M Davitt wrote:
>

>> paul c wrote:
>>
>>> J M Davitt wrote:
>>>
>>>> paul c wrote:
>>>>
>>>>> Bob Badour wrote:
>>>>> ...
>>>
>>> Maybe instead of saying "defining a header", I should have said "in 
>>> advance of entering a header".  I had in mind that an "empty" header 
>>> would be assumed.
>>
>>
>> Empty heading: like DEE and DUM have empty headings?
>> ...

>
>
> Yes. (Sorry, I should have said heading instead of header.)
>
>
>>> My peculiar view doesn't require me to ask "what is the predicate of 
>>> such and such a relation".  This will sound ridiculous to most people 
>>> I think because one would ask "well, what good is a database whose 
>>> predicates we don't know?".  OTOH, one aspect that for me defines a 
>>> relational engine is precisely that it must not circumscribe even in 
>>> the most indirect of ways what predicate a particular relation has, 
>>> its whole value is in being to manipulate relations without knowing 
>>> that - otherwise it would be an application!
>>
>>
>> Well, in that regard, it's already done -- in DEE ad DUM, no?  And I
>> think it's correct - but somewhat confusing - if you want other names 
>> for those relation values.

>
>
> (For a few years, I had trouble remembering which of DEE and DUM had a
> tuple and which didn't. Now whenever I forget, I just type the table
> names into google and up pops dbdebunk. I'm still not sure whether
> relations called TRUE and FALSE would cause confusion with the REAL TRUE
> and FALSE.)
>
>
>>
>> It almost seems as though you want to declare an analogue for DUM,
>> syntax-check some expressions, and add attributes to your relation
>> with the confidence that your expressions are still correct.
>>

>
> Not exactly how I thought of it, but I think that's fair, after all, one
> can add attributes, subject to one's external conception, to relation
> definitions that don't have empty headings, in fact not that the
> observation is of any use, that seems to be what happens when one
> defines a relation with one attribute.

I suggest an empty candidate key in a relation with any number of attributes is closer. Received on Thu Jun 29 2006 - 16:41:55 CDT

Original text of this message

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