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Re: Clean Object Class Design -- What is it?

From: Bob Badour <bbadour_at_golden.net>
Date: Sat, 1 Sep 2001 22:52:50 -0400
Message-ID: <S9hk7.637$_H1.127246633@radon.golden.net>

Adrian Veith wrote in message <9mqjbh$dl9$02$1_at_news.t-online.com>...
>"Bob Badour" <bbadour_at_golden.net> schrieb im Newsbeitrag
>news:6QTj7.601$Ny1.123682876_at_radon.golden.net...
>>
>> I disagree that constraint declaration is programming. The ISO standard
>> vocabulary requires a program to have both declarations and instructions
>to
>> satisfy some particular task. A constraint declaration is not a program
>any
>> more than a conceptual analysis is a program.
>
>To make a distinction between a declaration and short method is quite
>needless.

I disagree. They are fundamentally different, and one can easily declare constraints that no short method could enforce.

>> I understand that ODBMSes require one to program in order to enforce
>> integrity because they generally treat integrity enforcement as nothing
>more
>> than a sub-task in every other task (or method, if you prefer).
>
>I can see no reason, why a OODB should not have constraint declarations.

Relations and the relational algebra provide a very powerful means for constraint declaration. What does OODB have to offer in comparison?

>But the point is, if this is usefull ?

Of course, it is. Otherwise, how does the DBMS prevent a DBA from screwing up the data by mistake? Or do you only hire infallible DBAs?

>The advantage of checking constraints in a method is, that the checking can
>be done at the client side.

Nothing prevents client-side enforcement of declared constraints, which makes this a non-advantage.

Method-based constraints do not prevent a DBA from writing a new method that violates the existing known integrity rules.

>Checking constraints at the server side is not
>that effective and in general limited.

This is an extraordinary statement that contradicts considerable empirical evidence. On what do you base the statement?

>If you define integrity, that a certain value is inside a given range, than
>the concept of constraint declarations is enough.

This barely scratches the surface of constraint declaration.

>But if things are getting
>more complex this concept fails. (SQL fails!).

Of course, SQL fails. SQL utterly failed to provide relational constraint declaration just as it failed to deliver most of the relational model. Received on Sat Sep 01 2001 - 21:52:50 CDT

Original text of this message

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