Re: How to unnest an array with element indexes
| От | Pavel Stehule |
|---|---|
| Тема | Re: How to unnest an array with element indexes |
| Дата | |
| Msg-id | CAFj8pRDRzVNJcbqomgNNCOcriJe_BmuxPPny1fm1tOr7BzPqKQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: How to unnest an array with element indexes (AlexK <alkuzo@gmail.com>) |
| Ответы |
Re: How to unnest an array with element indexes
|
| Список | pgsql-sql |
Hello
Simple plpgsql function can helpscreate or replace function unnest_rownum(anyarray)
returns table (id int, element anyelement) as $$
begin id := 1;
foreach element in array $1 loop
return next;
id := id + 1;
end loop;
return;
end $$ language plpgsql;
postgres=# select * from unnest_rownum(ARRAY[1,1,2,3,4,1,2,7]);
id | element
----+---------
1 | 1
2 | 1
3 | 2
4 | 3
5 | 4
6 | 1
7 | 2
8 | 7
(8 rows)
postgres=# select * from unnest_rownum(ARRAY['A','B','C']);
id | element
----+---------
1 | A
2 | B
3 | C
(3 rows)
Pavel
2014-02-19 20:57 GMT+01:00 AlexK <alkuzo@gmail.com>:
David,
The array stores a time series of values for consecutive days. All I need is
take an array such as ARRAY[1.1,1.2] and return to the client the following
series_start_date + (array_index-1), array_value
Based on what you are saying, the following should do it:
with pivoted_array AS(
select unnest(ARRAY[1.1,1.2])
),
indexed_array AS(
select
row_number()OVER() AS element_index,
unnest as element_value
from pivoted_array)
SELECT
(DATE '2014-02-19' + INTERVAL '1d'*(element_index-1)) AS
series_date,
element_value AS series_value
FROM indexed_array
Can you confirm that this behavior is guaranteed and documented. I could not
find it in the docs.
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