Re: No exceptions?
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Thu, 29 Jun 2006 21:41:55 GMT
Message-ID: <DOXog.3864$pu3.91530_at_ursa-nb00s0.nbnet.nb.ca>
>
>
> Yes. (Sorry, I should have said heading instead of header.)
>
>
>
>
> (For a few years, I had trouble remembering which of DEE and DUM had a
> tuple and which didn't. Now whenever I forget, I just type the table
> names into google and up pops dbdebunk. I'm still not sure whether
> relations called TRUE and FALSE would cause confusion with the REAL TRUE
> and FALSE.)
>
>
>
> Not exactly how I thought of it, but I think that's fair, after all, one
> can add attributes, subject to one's external conception, to relation
> definitions that don't have empty headings, in fact not that the
> observation is of any use, that seems to be what happens when one
> defines a relation with one attribute.
Date: Thu, 29 Jun 2006 21:41:55 GMT
Message-ID: <DOXog.3864$pu3.91530_at_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 - 23:41:55 CEST