Re: In an RDBMS, what does "Data" mean?

"Anthony W. Youngman" <wol_at_thewolery.demon.co.uk> wrote in message news:pKOdZaHNSQvAFwH7_at_thewolery.demon.co.uk...
> And the problem I have is that I cannot see any metaphysical interface
> between reality and relational theory. This is basically Dawn's point
> about "is relational theory even the right theory to use?".
>
> As for Gene, I agree we need a theory, and actually, I think relational
> theory is a great theory. Unfortunately it is a theory about a - call it
> abstract, call it imaginary, they're the same thing - concept called
> "data" that does not seem to have any basis in the real world.
>
> So what do I think should replace it? Nothing actually, we can just
> improve it. BUT IN DOING SO, IT WILL BE TRANSFORMED BEYOND RECOGNITION
> :-)

So what improvements would you make? From what I've heard suggested elsewhere, it's not a transformation beyond recognition.

> What we NEED is a "theory of business analysis" - a formal theory that
> tells analysts how to analyse the real world.

hahahahahahahaha

Oh... you're serious?

> And I'm pretty damn
> confident that you can NOT create a theory that will do a reversible
> mapping between the real world and relational data.

So what precisely is different about other theories of data that do allow a reversible mapping? And are there properties other then reversibility that are desirable in such a model?

> This theory will then be the equivalent of Kepler and Newton discovering
> ellipses and calculus, or of Einstein realising that mass and energy
> were interchangeable. Basically, pretty much ALL of relational theory's
> axioms are taken as given by the mathematicians, and no thought is given
> as to whether they actually match the real world.

Which axioms don't match? I wasn't really aware there were axioms per se.

> To give you a simple example, the business analyst analyses an invoice,
> and you design the database to store the data. Can you then ask the
> DATABASE to give you the invoice data back?

Sure.

> Certainly with current
> relational databases accessed with SQL, you're relying on either an
> application programmed OVER the database, or a view which gives you
> multiple copies of data of which the original only had one.

Huh?

> Yes I know people are likely to say that "SQL is not genuine
> relational", but you're still relying on a view - even a valid
> relational one - or an application.

So what do you want - the invoice paper? Maybe we should just rely on scanners producing JPGs - non-lossy, of course.

> If we can't go - using formal theory - from the database back through
> the analysis to get back to the real world we started from, then we have
> no idea if our axioms are correct, and as Dawn says, we have no idea if
> relational theory is the correct theory to solve real world problems.

Most real-world problems are more than just round-trip regurgitation. Surely any trivial serialization scheme fits that bill?

> And as I said before, it we have no idea if it's the correct theory, why
> are we using it?

So what do we have that's correct? You mean the round-trip is your litmus test?

> Dawn was going on about faith. Do you have faith in
> business analysts to get the analysis correct, or would you rather have
> a formal, REVERSIBLE and PROVABLE (or testable, falsifiable, scientific,
> whatever term you want to use) logical theory to do it for you?

Sure. I also want to fly, eat infinite amounts of ice cream without gaining weight, and drive at very fast speeds with no possibility of injury.

• erk