Re: The wisdom of the object mentors (Was: Searching OO Associations with RDBMS Persistence Models)

From: Cimode <>
Date: 2 Jun 2006 09:39:47 -0700
Message-ID: <>

<< In my opinion SQL does a fabulos job even with poor system of  datatypes. VARCHAR2(20) what a humpback!>> You are rightfully entitled to your opinion so am I. I am not impressed at all by SQL for I face its limitations everyday. The fact that SQL is the best we have to get closer to relational implementation does not make me happy. Quite the opposite in fact.

<<I also don't see how particular SQL syntax quirks impede an ability to write assertions(constraints).>>
I gave examples but they seem to be unsufficient... I will supply you with some code on that as soon as possible.

Complex assertions can even be implemented via basic
> constraints (CHECK, UNIQUE, FOREIGN KEY) on materialized views.
Yes but at what cost?

        Redundant non intuitive code when constraints get more exhaustively implemented.

        Breaking independence between the physical and logical layer (materialized/indexed views)

*Complex* is a relative thing. Can you define user defined operators using SQL ? How do you define a data type as being another relvar using SQL ? How would the SQL DBMS implement operators on that? --> It can't.

<<Again, overthrowing SQL would require a deaper insight.>> Overthrowing SQL is not the point and it is not the intent. My intent is about trying to identify in OO mechanisms that could be useful paliating at known SQL weaknesses.

<<For example,
 what if we treat functions as relations? Shouldn't we write

 select ename, sal2 from emp, (sal2=2*sal) f  where f.sal = emp.sal

 as a "pure" relationaly styled version of

 select ename, sal*2 from emp>>
 I do not understand what you are actually

Is allowing predicates in the "where" clause give us any benefits?>>

I am not positive what you mean by the two last questions. Thank you for rephrasing them. I do not understand what predicate have to do with where condition.

Please do not consider me as anti-SQL as I am not. Just aware of its limitations. Received on Fri Jun 02 2006 - 18:39:47 CEST

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