# Re: Counting propositions

Date: Tue, 22 Jun 2004 10:14:47 -0700

Message-ID: <DZZBc.20$da4.283_at_news.oracle.com>

"x" <x-false_at_yahoo.com> wrote in message news:40d8642c_at_post.usenet.com...

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*> > > > 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.
*

> But not all bag operators can be decomposed in this way.

AVG - nonfundamental, can be expressed in terms of SUM
**STDDEV = SQRT(VARIANCE)
**

VARIANCE = (SUM(x*x)-(SUM(x)*SUM(x))/SUM(1))/(SUM(1)-1)

Do you need mere examples to be convinced that there are only 4 fundamental aggregate operators?

1. SUM = "+"* 2. MIN = "/\"* 3. MAX = "\/"* 4. LIST = "||"*

*> > >
*

> > > > How does COUNT(distinct x) fits in? It's just abuse of syntax by

those who

are reluctant to write a slightly lengthier expression with inline view.

Slight correction: It's just abuse of syntax by those who are reluctant to write a slightly lengthier [but more presize] expression with inline view. Received on Tue Jun 22 2004 - 19:14:47 CEST