Re: Negative Numbers in "Identity" or" Autonumber" fields

On Mar 21, 8:28 am, Bob Badour <bbad..._at_pei.sympatico.ca> wrote:
> Marshall wrote:
> > On Mar 21, 4:00 am, Bob Badour <bbad..._at_pei.sympatico.ca> wrote:
>
> >>Marshall wrote:
>
> >>>On Mar 20, 10:31 am, "JOG" <j..._at_cs.nott.ac.uk> wrote:
>
> >>>>[...] Nothing in a
> >>>>proposition should ever be hidden from the user. Propositions come
>
> >>>>from outside of the logical layer after all. If an attribute is an
>
> >>>>identifier then it clearly impacts on identifying items in the real
> >>>>world.
>
> >>>I buy the "nothing should be hidden" argument, but I can't
> >>>decide if a domain that only supports equality is hiding
> >>>anything or not.
>
> >>It has to have at least one possible representation.
>
> > Can you elaborate? Why does it need at least one?
> > What breaks if it doesn't?
>
> How does one express any literal without at least one possible
> representation?

Okay, sure, yes, that's a point. But that's more of a structural objection than a functional one. What breaks if a type doesn't have literals? What about the model requires literals?

In the case of equality, I can point to what exactly breaks if a type doesn't support it: join. Specifically equijoin requires some kind of "equi-".

What breaks if a type doesn't have literals?

I'm not particularly attached to this construct, but if it is flawed I'd like to be able to put my finger right on it.

Marshall Received on Wed Mar 21 2007 - 17:24:44 CET