Re: Another view on analysis and ER
Date: Thu, 6 Dec 2007 04:19:48 -0800 (PST)
On Dec 6, 10:58 am, "David Cressey" <cresse..._at_verizon.net> wrote:
> "Jon Heggland" <jon.heggl..._at_ntnu.no> wrote in message
> > Quoth David Cressey:
> > > "Jon Heggland" <jon.heggl..._at_ntnu.no> wrote in message
> > >news:fj6737$o2p$1_at_orkan.itea.ntnu.no...
> > >> Quoth David Cressey:
> > > Not all modeling is analysis. Some of it is design. In particular, I'm
> > > going to claim that you discover attributes, but you design relvars.
> > > already have the second claim confirmed by Bob and others.
> > Yet when are discovering attributes, you presumably write them down
> > somehow. Is it the case that if you do it using E/R notation, you are
> > doing analysis, but if you do it using some relation- or predicate-based
> > representation, you are doing design?
> > Or perhaps it's simpler: Analysis is what you're doing when you're
> > talking with the subject matter experts; design is what you're doing
> > when you're not. :)
> > > Bob's distaste for pretty pictures should not obscure the mian theme. A
> > > model isn't a "pretty picture" as such. Rather, a "pretty picture" is
> > > projection of a model on a flat screen. Other projections have been
> > > proposed. A table written on a whiteboard, with some imaginary sample
> > > written into it, proposed by another participant, is another
> projection of
> > > a model on a flat screen.
> > Ceci n'est pas une pipe... Then is the model wholly intangible, existing
> > only in a platonic sense inside the designers (or analyst's) head? Never
> > mind, I see your point---but that doesn't answer my question: When is
> > modelling design, and when is it analysis? A bald statement that
> > relation-based models are designed doesn't cut it, even if it is
> > seconded; I need rational arguments.
> If you are modeling features of the problem, it's analysis. If you are
> modeling features of both the problem and the solution, it's design.
"Entity-relationship (ER) modeling is a widely accepted technique for conceptual database /design/." Received on Thu Dec 06 2007 - 13:19:48 CET