Re: Why is "group by" obligatory in SQL?
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Fri, 24 Jul 2009 15:08:27 -0300
Message-ID: <4a69f8a0$0$23760$9a566e8b_at_news.aliant.net>
>
> 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
>
>
> I didn't have performance in mind.
Date: Fri, 24 Jul 2009 15:08:27 -0300
Message-ID: <4a69f8a0$0$23760$9a566e8b_at_news.aliant.net>
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