Re: Object-oriented thinking in SQL context?
Date: Wed, 10 Jun 2009 11:08:19 -0300
> On 10 Jun, 00:12, "Walter Mitty" <wami..._at_verizon.net> wrote:
>><dr.coff..._at_gmail.com> wrote in message >> >>news:35fe9916-b423-49e4-95f4-b42bf672a4c7_at_x5g2000yqk.googlegroups.com... >> >>>That's what confused me. The general concepts are *similar* >>>to concepts from OO, but not the same. I suppose the main >>>difference is that objects are local collections of different >>>attributes, while in relational databases the objects are >>>'disassembled' and the attributes distributed over the >>>various tables. >> >>If the mapping between OO concepts and RM concepts were simple, someone >>would have, by now, written a book that ties the two of them together, and >>explains both patterns in terms that makes sense. to someone coming from one >>pattern or the other. To my knowledge, there is no such book. I'm going to >>echo something Bernard said in another response. >>Better minds than mine have attempted to reconcile the OO way of thinking >>and the RM way of thinking with each other. By their own reckoning, their >>attempts have been unsuccessful.
> I can see your point, now that Bernard and you kindly have
> taken the time to explain it.
Frankly, your biggest problem is not knowing who to ignore and who to pay attention to.
> Again, the concepts are so
> *similar* that it's an obvious idea to anyone coming from the
> OO side to at least ask why they aren't expressed in OO form.
> And again, I start to get an impression what the problem is:
> OO philosophy is founded on 'encapsualization', where attributes
> are collected into 'objects' that make some sort of sense in
> the problem (business) domain. Relational databases are all
> about breaking that encapsualization, to efficiently search
> for information.
Your ignorance is showing. "Encapsulation" is just a syntactic/physical implementation of a specific type of the general engineering principle of "information hiding". The RM addresses the same principle much more powerfully and much more completely through data independence.
>>So you really shouldn't expect to reduce RM to a pattern that you already >>know. And you shouldn't expect, based on your success with OO up to this >>point, to be able to treat RM as something that can be marginalized as >>either a specialized niche or a trivial development. It is neither.
> Oh, I never said RM is trivial! I only said the building
> blocks are, which means the inter-relations between tables
> that are trivial when seen in isolation, become complex.
> A brick might be trivial; A structure built from bricks,
> like Hagja Sophia, is not.
A brick is trivial. An n-dimensional relation of "object" values is not. You seem rather impervious to grasping the simplest of observations even when pointed out to you. Received on Wed Jun 10 2009 - 16:08:19 CEST