Re: count(boolean)

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От Jean-Luc Lachance
Тема Re: count(boolean)
Дата
Msg-id 3CE91F49.DC7B73C8@nsd.ca
обсуждение исходный текст
Ответ на Re: Casting timestamp  ("Joel Burton" <joel@joelburton.com>)
Список pgsql-sql
Actually, "count" should be "sum"

SELECT question_id AS id, sum( case when value then 1 else 0 end) as count_true, sum( case when value then 0 else 1
end)as count_false
 
FROM answers_boolean
GROUP BY question_id;


I wrote:

> 
> Dan,
> 
> Try:
> 
> SELECT
>   question_id AS id,
>   count( case when value then 1 else 0 end) as count_true,
>   count( case when value then 0 else 1 end) as count_false
> FROM
>   answers_boolean
> GROUP BY
>   question_id;
> 
> jll
> 
> Dan MacNeil wrote:
> >
> > I have a table answers_boolean:
> >
> >  question_id   | integer   | not null
> >  evaluation_id | integer   | not null
> >  value             | boolean |
> >
> > I'd like output in the form:
> >
> > question_id,  count_true, count_false
> >
> > ....where count_true is the number of questions answered "true"
> >
> > SELECT
> >     question_id AS id, value AS val , count(value) AS cnt
> > FROM
> >      answers_boolean
> > GROUP BY
> >      question_id,value;
> >
> > gives me:
> >  id | val | cnt
> > ----+-----+-----
> >   2 | f   |   3
> >   2 | t   |   3
> >   3 | f   |   2
> >   3 | t   |   4
> >
> > ...which is sorta what I want.
> >
> > I've looked through the docs & archive but haven't found the answer.
> >
> > TIA
> >
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