"Adrian Kubala" <adrian_at_sixfingeredman.net> wrote in message
news:slrnc03i64.ov7.adrian_at_sixfingeredman.net...
> Dawn M. Wolthuis <dwolt_at_tincat-group.com> schrieb:
> >
> > "Adrian Kubala" <adrian_at_sixfingeredman.net> wrote in message
> > news:slrnc01db2.k9f.adrian_at_sixfingeredman.net...
> >> Dawn M. Wolthuis <dwolt_at_tincat-group.com> schrieb:
> >> > With this discussion, I've been focussed on one specific issue,
> >> > where the database model I am using has been taken to task for not
> >> > employing relations. I have no problem stating that it does not
> >> > 100% follow a relational database model, however, this one point --
> >> > that it does not employ relations is entirely false.
> >>
> >> That's like calling a black and white camera a "color camera" because
> >> black and white are colors.
> >
> > Most certainly not. First of all, black and white are not typically
> > considered colors by color professionals, I believe.
> >
> > I will be the first to say that the Nelson-Pick model does not meet the
> > criteria of the relational database model. But it is absolutely the
case
> > (if you accept my analysis that it is based on functions, I think you
will
> > agree) that it is a mathematically relational model, right?
>
> It does not allow you to express *any* relation, therefore it is not
> relational, in exactly the same way that a camera which only lets you
> take pictures of pink is not a color camera. If your model let you
> express mathematical relations instead of "Codd relations", then I would
> agree with you, but since there are mathematical relations which your
> model cannot express, it's wrong to call it relational.
>
> Especially since it seems your intent in doing so is to imply that it is
> just as expressive as the relational model, when in fact it is strictly
> less expressive. (Not to imply any value judgement, but simply to convey
> the fact that there are relations which your model cannot possibly
> express but any relational model can, whereas any function that your
> model can express, any relational model can as well.)
Even if it could express them, it expresses them with greater complexity and
less facility.
Received on Mon Jan 12 2004 - 16:07:33 CST
