Re: Extending my question. Was: The relational model and relational algebra - why did SQL become the industry standard?

Lauri Pietarinen wrote:
>Jan Hidders wrote:
>>Lauri Pietarinen wrote:
>>
>>>I can't get into all the details here but there
>>>there is lot's of discussion on different issues relating
>>>aggregates in
>>>Relational Database Writings 1994-1997
>>>(ISBN 0-201-39814-1) installments 44, 45 and 50.
>>
>>I'm not much impressed by those references. The whole point of our
>>discussion was to see how well their arguments stand up to critical
>>examination. Since you apparently don't want to go into the specific issue
>>that we were disussing I now get the feeling that you want to avoid that
>>discussion.
>>
>>Pity.
>
>I was not really trying to impress you by those references. I was just
>figuring that since we were talking about aggregates we should have some
>reference (if not agreement) as to what an aggregate function means.

Why do you think there is disagreement about that?

>Regarding sets<-->bags in general I would sum up my arguments followingly:
>
>1) SQL operates in two modes: "bag"-mode and "set"-mode

Where do you get this idea from? There is just one mode: the bag mode.

>Regarding point 5) I challenge you to give me just
>*one* *real* *world* *example* in which duplicates
>would actually be of use to the end user.

I never said there was, and even if there was you could simulate this in a set-only model.

So, what is your point exactly?

• Jan Hidders