Re: Counting propositions
Date: Tue, 22 Jun 2004 19:31:48 +0300
Message-ID: <40d85df1$1_at_post.usenet.com>
"Mikito Harakiri" <mikharakiri_at_iahu.com> wrote in message
news:DPYBc.18$da4.141_at_news.oracle.com...
>
> "Paul" <paul_at_test.com> wrote in message
> news:CFWBc.19053$NK4.3265189_at_stones.force9.net...
> > Isn't "select count(*)" a similar thing? You should explicitly name the
> > data columns you want. If you change the candidate keys it may change
> > the whole interpretation of the propositions. In which case it may no
> > longer be true that you want to count propositions.
>
> Count is unusual aggregate operator. Every other aggregate operator is
> associated with a binary operation. Indeed, the SUM is iterative
application
> of "+", the MAX is iterative application of "max(x,y)" (or CASE ...).
There
> are few exceptions like AVG, but they can be viewed as redundant (or at
> least less fundamental) operators.
SUM(),MAX(),AVG() apply to a bag of values.
> What operation COUNT is application of? The increment, of course. Unlike
the
> examples above, the increment is unary operation, so the COUNT shouldn't
> really have an argument!
COUNT() apply to a bag of values.
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