Re: Time Aggregates

"Thomas Lockhart" <lockhart@alumni.caltech.edu> replied to:
"Itai Zukerman" <zukerman@math-hat.com>

> > I'm currently doing this:
> >   SELECT symbol, date_trunc('minute', posted),
> >          min(price), max(price), avg(price)
> >   FROM trade
> >   GROUP BY symbol, date_trunc('minute', posted);
> > to get a list of minute-averages of trade prices.  I get the feeling
> > that this is bad form, that I should be doing this some other way.  Is
> > that the case?
>
> Looks OK to me. If you are doing this *a lot* (i.e. many more queries
> than inserts), then you might want to set up another column which
> contains date_trunc('minute',posted) to avoid the calculation. Something
> like
>
>   create table trade (
>     symbol text,
>     posted timestamp,
>     price integer,
>     mpost  timestamp
>   )
>
> then define a rule to update mpost when posted gets set (haven't done
> that part).

Tom,

I want to have two inputs to a table -- 5 widgets at 6 dollars, nextline,7
widgets at 45 dollars, nextline 1 widget at 4...sort of thing -- and output
to screen the $30, $315, $4 with those last three numbers also going back
into the database.

Is there any way of doing this withing the SQL, or does it have to be
written in a scipt external to the database itself?
                                                 Cheers,
                                                            -dlj.