Accessing array elements in a FOR PL/pgsql loop
For each element in the array, I need to make some operation with plpgsql.
I usually use the syntax:
DECLARE
array_len int;
BEGIN
array_len := array_upper(i_array, 1);
FOR i IN 1 .. array_len
LOOP
SOME OPERATION (i_array[i])
END LOOP;
But I don't like that. Is there any built-in way to do that without
using the length, i.e like in python, e.g.
for element in array:
....
This example does not work in Postgres.
I think I need a built-in function to make a column from an array, like
in the backwards operation SELECT ARRAY(column)
In response to Igor Katson :
I think I need a built-in function to make a column from an array, like
in the backwards operation SELECT ARRAY(column)
By David Fetter:
CREATE OR REPLACE FUNCTION unnest(ANYARRAY) RETURNS SETOF ANYELEMENT
LANGUAGE SQL AS $$SELECT $1[i] FROM
generate_series(array_lower($1,1),array_upper($1,1)) i;$$;
HTH, Andreas
--
Andreas Kretschmer
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A. Kretschmer wrote:
In response to Igor Katson :
I think I need a built-in function to make a column from an array, like
in the backwards operation SELECT ARRAY(column)By David Fetter:
CREATE OR REPLACE FUNCTION unnest(ANYARRAY) RETURNS SETOF ANYELEMENT
LANGUAGE SQL AS $$SELECT $1[i] FROM
generate_series(array_lower($1,1),array_upper($1,1)) i;$$;HTH, Andreas
Thanks. I thought, there is a built-in one for that.
On Thu, 19 Feb 2009, Igor Katson wrote:
A. Kretschmer wrote:
In response to Igor Katson :
I think I need a built-in function to make a column from an array, like in
the backwards operation SELECT ARRAY(column)By David Fetter:
CREATE OR REPLACE FUNCTION unnest(ANYARRAY) RETURNS SETOF ANYELEMENT
LANGUAGE SQL AS $$SELECT $1[i] FROM
generate_series(array_lower($1,1),array_upper($1,1)) i;$$;HTH, Andreas
Thanks. I thought, there is a built-in one for that.
there is, but in CVS HEAD
psql (8.4devel)
Type "help" for help.
postgres=# select unnest('{1,2,3}'::int[]);
unnest
--------
1
2
3
(3 rows)
Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83