Re: Why is "group by" obligatory in SQL?

From: Bob Badour <>
Date: Fri, 24 Jul 2009 15:08:27 -0300
Message-ID: <4a69f8a0$0$23760$>

paul c wrote:

> Bob Badour wrote:
> ...

>>> Right, it becomes our problem  It is very clear that he allowed 
>>> 'inserts' wrt some relations but not 'deletes', and vice-versa for 
>>> other relations.  That is a big loophole if you ask me, like when you 
>>> ask one of the locals for directions to the next town and he  answers 
>>> "you can't get there from here".  Contradicts what Codd called 
>>> relational closure.
>> Where exactly did he do this? It's something you have mentioned 
>> several times, but I am unfamiliar with the reference.
>> ...

> In his 1990 book, in one of the later chapters (around chapter 20 if I
> recall, haven't got the pdf right now) to do with views, he basically
> agrees with what Hugh Darwen says about inserting to a union.
> Admittedly, he didn't call this a contradiction, but it is there
> nonetheless!
> ... (I don't believe the question is as obvious as many RT
>>> advocates suggest, there is more to it than trying to make sure the 
>>> dbms is authoritative.)
>> Such as? If you are going to say performance, then I would point out 
>> the dbms needs to extend to the client computer to enforce constraints 
>> without a round-trip to some server.

> I didn't have performance in mind.

Okay, so you didn't have performance in mind. What did you have in mind? Received on Fri Jul 24 2009 - 20:08:27 CEST

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