Re: Add calculated fields from one table to other table
От | Richard Broersma Jr |
---|---|
Тема | Re: Add calculated fields from one table to other table |
Дата | |
Msg-id | 534177.87743.qm@web31809.mail.mud.yahoo.com обсуждение исходный текст |
Ответ на | Re: Add calculated fields from one table to other table (roopa perumalraja <roopabenzer@yahoo.com>) |
Ответы |
Re: Add calculated fields from one table to other table
Re: Add calculated fields from one table to other table |
Список | 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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