Re: No exceptions?

From: paul c <>
Date: Thu, 29 Jun 2006 21:32:12 GMT
Message-ID: <wFXog.109417$IK3.45509_at_pd7tw1no>

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.

p Received on Thu Jun 29 2006 - 23:32:12 CEST

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