From: | Sergey Burladyan <eshkinkot(at)gmail(dot)com> |
---|---|
To: | "Dmitry E(dot) Oboukhov" <unera(at)debian(dot)org> |
Cc: | pgsql-ru-general(at)postgresql(dot)org |
Subject: | Re: аггрегатор по аггрегаторам |
Date: | 2012-04-13 14:06:15 |
Message-ID: | 87zkafbuaw.fsf@seb.koffice.internal |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-ru-general |
"Dmitry E. Oboukhov" <unera(at)debian(dot)org> writes:
> например:
>
> select * FROM (VALUES (ARRAY[1,2,3,3,4]), (ARRAY[1,2,2,3,4])) t;
> column1
> -------------
> {1,2,3,3,4}
> {1,2,2,3,4}
> (2 rows)
>
>
> WITH "a" AS (select * FROM (VALUES (ARRAY[1,2,3,3,4]), (ARRAY[1,2,2,3,4])) t )
> SELECT array_agg(unnest(column1)) FROM "a";
>
> ERROR: set-valued function called in context that cannot accept a set
Нужно больше уровней вложенности:
WITH "a" AS (select * FROM (VALUES (ARRAY[1,2,3,3,4]), (ARRAY[1,2,2,3,4])) t )
SELECT array_agg(n) from (select unnest(column1) as n FROM "a") as x;
> И второй вопрос:
>
> допустим имеется массив:
>
> {1,2,3,3,4,1,2,2,3,4}
>
> Как можно посчитать число уникальных элементов в нем?
>
> SELECT COUNT(DISTINCT unnest(ARRAY[1,2,3,3,4,1,2,2,3,4]))
>
> дает ту же ошибку
SELECT COUNT(DISTINCT n) from (select unnest(ARRAY[1,2,3,3,4,1,2,2,3,4])) as x(n);
--
Sergey Burladyan
From | Date | Subject | |
---|---|---|---|
Next Message | vlads | 2012-04-25 00:59:08 | Остатки товара. |
Previous Message | Sergey Konoplev | 2012-04-13 13:42:19 | Re: [pgsql-ru-general] аггрегатор по аггрегаторам |