Re: relational reasoning -- why two tables and not one?

lawpoop wrote:
> On another mailing list about a database which shall not be named, a
> poster asked about a single-table database structure. It was to track
> donations, and that thank-you letters had been sent in reply.
>
> A couple folks ( myself included ) thought that there should be at
> least two tables -- 'donors' and 'donations' . But the poster argued
> that no, there would never be a holiday fund drive appeal sent out to
> all donors, or a year-end statement, or anything of that sort. So a
> single table would suffice.
>
> I tried to argue the point that having 'donors' and 'donations' more
> accurately modeled 'reality' , and failed. Another poster, who was in
> fact in favor of two tables, argued against the 'modeling reality'
> argument, saying that theorists would it's wrong to have
> 'donation_dates' as a separate table, even though the relationship "in
> reality" is one date for many donations. If it meets the functionality
> specs, it's fine.
>
> ( There was talk of needing Donors as an entity later on, but there
> was no need for it in the specs now, so it's moot ).
>
> I couldn't think of a good argument against it, so I must be wrong.
> But my gut instinct or intuition is telling me there is some
> understanding of relational theory or something that I am not
> grasping, which would prove insightful in this discussion.
>
> Thoughts and comments?

Whose reality? Also, theory doesn't dictate requirements. As Ralston Saul suggests, there has been no such thing as absolute reality since a few hundred years ago. When Date writes about modelling reality, I think he means it very loosely. Reality as a target risks inventing imaginary requirements although I realize there is a going industry based on foisting that on users. Apparently the poster eliminated a number of possible requirements so a single table doesn't seem unreasonable given the 'meagre' information as Bob B put it, even if some donors are repeat donors. Received on Thu Oct 15 2009 - 03:29:08 CEST