Re: database design
Date: Sat, 02 Sep 2000 19:14:55 GMT
Message-ID: <8orjj4$4cq$1_at_nnrp1.deja.com>
In article <LI8s5.1066$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.
A grocer probably wants to keep information about his suppliers,
vegetables, customers and such.
A martian wants to keep track of the spaceships, stars and earthlings.
In case you define a conceptual model in such a way ANY application can
be built afterwards. Again, this goes for conceptual models. As soon as
you have to build an application system for (part of) this information
model and once you have chosen a platform, you'll have to transform the
conceptual model into a physical model and transform that into a
database schema and both transformations will need special DBA skills
to adjust the models so that the end-result is an award-winning
database.
So, when you use "database design" only for the implementation you are
right. But when database design covers the whole track from analysis to
implementation then you might even HAVE to start designing before any
application has been determined.
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Received on Sat Sep 02 2000 - 21:14:55 CEST