very good ! ;-)
"Brian E Dick" <bdick_at_cox.net> schrieb im Newsbeitrag
news:_qmL9.32292$0b.1285409_at_news2.east.cox.net...
> BTW, the table for the query below is
>
> create table daily_hits
> (hit_day date
> ,hits number)
>
> hit_day is truncated to the day
>
> To verify the query I ran it for a=0 and a=1. Those queries yielded
> exp_avg=a.hits and exp_avg=avg(b.hits), respectively. So, I am confident
> that this query is correct.
>
> "Brian E Dick" <bdick_at_cox.net> wrote in message
> news:Q4mL9.32187$0b.1277768_at_news2.east.cox.net...
> > I believe the following does it for n=60 and a=0.5.
> >
> > select a.hit_day
> > , sum(b.hits * power(0.5, a.hit_day - b.hit_day))
> > / sum(power(0.5, a.hit_day - b.hit_day)) exp_avg
> > from daily_hits a
> > , daily_hits b
> > where b.hit_day between a.hit_day - 59 and a.hit_day
> > group by a.hit_day
> >
> >
> > "Laly" <laly.kattoor_at_freesbee.fr> wrote in message
> > news:4ec940f.0212111138.1658f90d_at_posting.google.com...
> > > Hi,
> > >
> > >
> > > Does anyone know how i can compute an exponential average using
> > > analytical functions under Oracle. It is easy to get normal moving
> > > average with avg(...) over(partition by ... order by ... rows 60
> > > preceding) but how about getting :
> > > x(n) + a*x(n-1) + a^2*x(n-2)+....
> > > -----------------------------------
> > > 1 + a + a^2 + ...
> > >
> > >
> > > More generally, is it possible to compute a column using the value
> > > just computed in the row before ? Something like x(n+1) = f(x(n))
> > > where n is the number of the row ?
> > >
> > >
> > > Thanks by advance for any clue.
> > >
> > >
> > > Laly.
> >
> >
>
>
Received on Tue Dec 17 2002 - 14:10:03 CST
