From: Richard Broersma Jr <rabroersma@yahoo.com>
To: roopa perumalraja <roopabenzer@yahoo.com>
To: pgsql-sql@postgresql.org
Cc: Richard Broersma Jr <rabroersma@yahoo.com>
Subject: Re: Add calculated fields from one table to other table
Date: Sun, 29 Oct 2006 19:12:51 -0800 (PST)
Message-ID: <534177.87743.qm@web31809.mail.mud.yahoo.com> (raw)
In-Reply-To: <20061030025049.56769.qmail@web50803.mail.yahoo.com>
> 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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To: pgsql-sql@postgresql.org
Cc: rabroersma@yahoo.com, roopabenzer@yahoo.com
Subject: Re: Add calculated fields from one table to other table
In-Reply-To: <534177.87743.qm@web31809.mail.mud.yahoo.com>
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