Re: Mixing OO and DB

On Mar 16, 7:02 am, "Brian Selzer" <br..._at_selzer-software.com> wrote: []
> This is how redundancy creeps into a database. It's often tempting to just
> add a column or a table without checking to see if the information that
> would be recorded in that column or table isn't already available somewhere
> else.
>
> > It isn't until you take a database centered viewpoint that you begin to
> > assess the entire schema from an information point of view.
That *centralized entire schema* is called logical layer in RM.

> Maybe that's what's lacking in OOP.
Among a million other things what is lacking in OO is a clear distinction of the physical and logical layer of information. And if such concepts were defined clearly in OO, then OO would be a poor copy of RM.

> > In fact, it's an oversimplification to say that the schema is "part of"
> > multiple applications.
>
> I see your point. I'm not sure I agree. An application can have access to
> the entire database even if it only interacts with part of the database.
>
>
>
> > An analogous thing happens when a single application interacts with
> > multiple
> > databases.
>
> I think that there is only ever one database. There's nothing that says
> that there can't be two separate disjoint sets of relations in the same
> database. What appears from one perspective to be multiple databases, can
Several schema's are to be perceived as one single complex relation in a logical RM perspective. Received on Sun Mar 16 2008 - 14:29:33 CET