Re: database design

Jan Lenders <J.Lenders_at_Betuwe.net> writes:

> In article <LI8s5.1066$q4.59210_at_petpeeve.ziplink.net>,
 

> "David Cressey" <david_at_dcressey.com> wrote:
> snip
> > Likewise, when you design a database without an application in
> > mind, you are guessing about what use the information will be put
> > to. I think it's possible, but it's likely that the guess will be
> > somewhat wrong.
 

> I'm sorry, but I do not agree for 100% on that. A logical database
> design (a conceptual model using any technique; UML class-diagram,
> ERM/PERM et cetera) should be the representation of the entities and
> their relationships in your vision of (a part of) the
> reality. Preferably only those entities and relationships for which
> you might want to keep information about.
[...]

Here is one way to go astray (Which Jan Lenders forgot):

Office system:

You create nice database of chairs, desks, projector screens etc.

First app you need turns out to be "Track employees whereabouts so receptionist can give intelligent answers" ---- Goofed.

OR

First app turns out to be: Track available facilities so we can plan conferences. ---- You might actually be in luck.

This is why "might want to keep" in Jan Lenders Article needs thinking about. This is another way of "guessing about the application". So David Cressey is correct.

-- 
Håkon Alstadheim, Montreal, Quebec, Canada