Re: Object-oriented thinking in SQL context?

From: Bob Badour <>
Date: Wed, 10 Jun 2009 11:08:19 -0300
Message-ID: <4a2fbe57$0$23754$> wrote:
> On 10 Jun, 00:12, "Walter Mitty" <> wrote:

>><> wrote in message
>>>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

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