Re: Decline of Science: Computer Science and Databases

Carl,

OK, I think I understand now.

Regarding the last example:

> > > public ObjectSet dualClass() {
> > > Query q = db.query();
> > > q.constrain(Consultant.class).or(q.constrain(Coach.class));
> > > q.descend("salary").constrain(new Double(200000)).greater();
> > > return q.execute();
> > > }
>
> SELECT FROM Consultant, Coach WHERE .salary > 200000;

Is'nt it rather a union than a join?

( select .. from constultant where ... union select ... from coach where ...) ??

As a general remark I would say that the relational approach requires more planning in the sense that you have to design and create a database schema (=data modelling). However, the reward is that

• extremely complex queries can be formulated
• arbitrary integrity constraints can be enforced ( referential integrity being only the simplest case)
• queries can be optimised by an optimizer

How does this fit in with OO-programming? Well, the idea actually is to get rid of programming as much as it is possible ;-)

regards,
Lauri Received on Mon Nov 04 2002 - 12:09:51 CET