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"Mikito Harakiri" <mikharakiri_at_iahu.com> wrote in message
news:DZZBc.20$da4.283_at_news.oracle.com...
> "x" <x-false_at_yahoo.com> wrote in message news:40d8642c_at_post.usenet.com...
> > **** Post for FREE via your newsreader at post.usenet.com ****
> > > > > 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.
>
> Let's go through the list:
>
> 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 = "||"*
Nonsense.
SUM([1])=1.
COUNT([1,2,3,4])=4 !=SUM([1,2,3,4]).
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Received on Tue Jun 22 2004 - 14:18:23 CDT
