Re: What does this NULL mean?

"mountain man" <hobbit_at_southern_seaweed.com.op> wrote in message news:C98qf.72848$V7.1218_at_news-server.bigpond.net.au...

> The only place the RM is evolving is in Date's head, and
> therefrom in the heads of his party of hangers on. However
> from an external and independent perspective, the RM has
> not changed since relational systems started selling oracle.

I disagree. You gave a pointer to an article where Date is compared to Codd's paper on adding more meaning to the relational system, leads me to believe that Codd has been revising and extending his original vision over the years. That pointer was from you, wasn't it?

However, there is nothing quite so conservative as a successful revolution. Codd's revisions have been cautious and constructive. I'm not so sure I can say the same thing about Date&Darwen's revisions.

>
> > does not address the application software enviroment because it is
> > completely independent to it.
>
> The code and the data are two sides of the one coin.
> They are like ying and yang. You and Date might like
> to think they are separate entities with different theoretical
> basis, but then you and Date have not given the matter
> enough thought IMO.
>

Absolutely right.

People whom I regard as smarter than I have attempted to reconcile the relational model of data with the object model of process (and encapsulated data). By their own account, they have not succeeded. Nevertheless, I believe that the "data centric" and the "process centric" views will be harmonized some time in the future, and I believe the something like the object model, but with a firmer theoretical base, will play an important role.

>
> > This is like to criticize the Relational
> > Model because it is mute about how to cultivate melons
>
> That's clearly impossible. The Relational Model is
> perfect and any criticism of it must be wrong.
>
>
> >>As I have been saying for some time, the relational model
> >>of the data is incomplete as a database systems theory for
> >>this century because essentially, things have changed. See:
> >>http://www.mountainman.com.au/software/history/relational_model_incom...
> >
> > This is plenty of incoherences, and the possibility of creating stored
> > procedures is in the definition of the Relational Model. It is an
> > essential part of the RM since the first day, although it was not
> > present in some of the first fatally flawed implementations.
>
> Application software may be reduced to stored procedures.
> Stored procedures are database objects, written in the SQL
> of the host vendor RDBMS software. They cannot be
> separated from the database.
>
> Thus you shoot yourself in the foot.
>
>
>
> >>No I want to see a properly extended theoretical relational model
> >>of both the data and the programs (because they are inextricably
> >>linked and optimally need to be managed, coordinated and change-
> >>managed together).
> >
> > Applications are external to the data models, but there is little to
> > theorize about the coordination between databases and applications: if
> > you change the logical view of the database then you have to adapt the
> > applications. That's all. You can create a tools that makes this
> > adaptations automatically, but it has nothing to do with data
> > management theory.
>
> Data management theory and stored procedure management
> theory are subsumed by the theory of database systems. This
> is why the relational model of data is only half the story wrt a
> complete theory of database systems.
>
>
> >>The only confusion that exists as a result of my posting
> >>appears to be with certain parties who are unable to
> >>rationally discuss the evolution of theory of the RM
> >>of data (as it was 30 years ago) into a far more
> >>powerful theory that addresses a greater spectrum
> >>of contemporary database systems issues.
> >
> > What you want is a theory for information systems development.
> > Something broader than the Relational Model. The Relational Model is a
> > part of that, and it does very well its specific job.
>
>
> What it does, yes, it does do well in its data centric
> world view. But so what? Why rest on its laurels
> like Date has been doing for 30 years?
>
>
>
>
> --
> Pete Brown
> Falls Creek
> OZ
> www.mountainman.com.au
>
>
Received on Wed Dec 21 2005 - 15:45:41 CET