From: Christoph Haller <ch@rodos.fzk.de>
To: david.bouriaud@ac-rouen.fr
Cc: pgsql-sql@postgresql.org
Subject: Re: SQL problem with aggregate functions.
Date: Thu, 11 Jul 2002 10:37:40 METDST
Message-ID: <200207110837.KAA07881@rodos> (raw)
In-Reply-To: <200207091036.17913.david.bouriaud@ac-rouen.fr>
>
> I've got a table in which there is a field that can have one amongst 3
> possible values : D, R, X. Is it possible to get in one query the count of
> this different values.Please, note that I don't want to have a querry like
> this :
> "select count (*) from tab group by f1;", cause i want to get all the possible
> count values in one row (these data are already grouped on another field).
> To give a more accurate example, here is what I want to retrieve :
>
> Field group | count of D | count of R | count of X.
>
> Any clues ?
> --
What about something like
SELECT SUM(f1_d) AS count_d,
SUM(f1_r) AS count_r,
SUM(f1_x) AS count_x
FROM (
SELECT CASE WHEN f1 = 'D' THEN 1 ELSE 0 END AS f1_d,
CASE WHEN f1 = 'R' THEN 1 ELSE 0 END AS f1_r,
CASE WHEN f1 = 'X' THEN 1 ELSE 0 END AS f1_x
FROM tab ) AS foo ;
Regards, Christoph
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To: pgsql-sql@postgresql.org
Cc: ch@rodos.fzk.de, david.bouriaud@ac-rouen.fr
Subject: Re: SQL problem with aggregate functions.
In-Reply-To: <200207110837.KAA07881@rodos>
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