Re: Do Data Models Need to built on a Mathematical Concept?

> You are confusing domains and relations.

I will explain my understanding so you may correct me.

I see a relation as a set(person).
Each tuple as an element(john, mary,..) of the set. A tuple's attributes(gender,height) are properties of the element(john).
The tuple itself represents john and no one attribute of the tuple is john.

A domain is the set of acceptable values for an attribute of a tuple.

> If you want to think about "things in reality" (not the best
> idea) then you should think of them as being individual
> values in the database. That is, what's in one specific attribute
> of one specific row of a relation is a "thing in reality." *Not*
> a row.

IMO, each tuple(row) can represents a thing in reality. A row itself in a table named Person represents a person, regardless of how many attributes it has. Received on Mon May 05 2003 - 01:55:19 CEST