From: | Richard Broersma Jr <rabroersma(at)yahoo(dot)com> |
---|---|
To: | roopa perumalraja <roopabenzer(at)yahoo(dot)com>, pgsql-sql(at)postgresql(dot)org |
Cc: | Richard Broersma Jr <rabroersma(at)yahoo(dot)com> |
Subject: | Re: Add calculated fields from one table to other table |
Date: | 2006-10-30 03:12:51 |
Message-ID: | 534177.87743.qm@web31809.mail.mud.yahoo.com |
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Thread: | |
Lists: | pgsql-sql |
> Thanks a lot for your help. The query does work, but now I have a problem. The query goes like
> this:
>
> select tk.ric, tm.timeseries_time, count(tk.*), avg(tk.price),
> sum(tk.price*tk.volume)/sum(tk.volume), sum(tk.volume)
> from ticks tk, timeseries tm where tk.tick_time >= tm.timeseries_time and
> tk.tick_time < (tm.timeseries_time + '1 minute' :: interval)::time group by tm.timeseries_time,
> tk.ric order by tk.ric, tm.timeseries_time
>
> The problem is, if there is no row for certain minute, then I want the count to be displayed
> as zero and other coulmns like avg to be null. In this query, it just omits those minutes which
> doesnt have any row for a particular minute.
You have to use an outer join. You will need a table or sequence that has every minute in a range
that you are interested in and outer join that to your actual table. This will give you a count
of zero.
i.e.
select S.minute, count(W.minute) as minutecnt
from Series_of_Minutes S left join Working_table W
on S.minute = W.minute
;
hope this helps.
REgards,
Richard Broersma jr.
ps. sorry that my query suggestion didn't work :0)
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