Re: A different definition of MINUS, part 4
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Fri, 09 Jan 2009 23:20:41 -0400
Message-ID: <49681419$0$5499$9a566e8b_at_news.aliant.net>
>
> I suspect so too. It's been many years since I used any SQL products
> much, maybe some of them have a relation comparison operation now, but I
> don't remember any. My hunch is that any implementation language that
> doesn't have such an op is not likely to be defined on much formal logic.
Date: Fri, 09 Jan 2009 23:20:41 -0400
Message-ID: <49681419$0$5499$9a566e8b_at_news.aliant.net>
paul c wrote:
> Bob Badour wrote:
> ...
>
>> The notation may also have some name scoping issues, but I think we >> are both on the same page about the relation equality comparison >> providing both quantifiers to the algebra.
>
> I suspect so too. It's been many years since I used any SQL products
> much, maybe some of them have a relation comparison operation now, but I
> don't remember any. My hunch is that any implementation language that
> doesn't have such an op is not likely to be defined on much formal logic.
I strongly doubt any SQL dbms supports table comparison. I have no doubt the vendors would say "That would be too slow and expensive" instead of doing their jobs. Received on Sat Jan 10 2009 - 04:20:41 CET