Re: Pizza Example

"Anthony W. Youngman" <wol_at_thewolery.demon.co.uk> wrote in message news:3liqSxG8WvfAFw3H_at_thewolery.demon.co.uk...
> I was thinking in terms of EAR - entity attribute relationship. How does
> the database know the difference between a table that describes an
> entity, and a table that describes a complex attribute of that entity
> (that has to be in a separate table because an entity can have multiple
> instances of it).

It doesn't. That's the point.

> I wasn't trying to model language, I was just making the point that
> language has words that represent something that has physical existence
> (nouns), and words that describe what that existence is like
> (adjectives). Relational theory uses tables to do both these tasks, and
> has no way of telling which task any individual table is fulfilling.

Right. That's the point.

> Okay, MV can't tell for certain, but it's a fairly safe bet that any
> random table is fulfilling the "noun" role not the "adjective" role.

That's not a safe bet, nor is it one you even need to make. That's the root of the E-R nonsense.

> And, for example with optimisation, if you gamble on that being the case
> then you will win big nine times out of ten.

Discussions of gambling in the context of data design are somewhat misplaced. Last I knew, we were trying to create order from chaos, not systematize the chaos.

• erk