Обсуждение: update several columns from function returning several values

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update several columns from function returning several values

От
Rémi Cura
Дата:
Hey,
a trivial question I guess,
can't make it work.

IF I define a function returning several values , I can't use it to update mutliple columns of a table at once.
i __don't__ want to use CTE or subquerry,
and of course I don't wan tto compute the function several time.

CREATE TABLE test_update_m_values (
gid int,
gid_plus_1 int,
gid_minus_1 int
);
 
INSERT INTO test_update_m_values VALUES (1,0,0) ;

CREATE OR REPLACE FUNCTION rc_test_update_m_values( gid int,OUT gid_plus_1 int, OUT gid_minus_1 int)
AS $$  -- @brief : test function, can be deleted
BEGIN
    SELECT gid+1,gid-1 INTO gid_plus_1, gid_minus_1; 
RETURN ;
END;
$$ LANGUAGE 'plpgsql' IMMUTABLE STRICT   ;


UPDATE test_update_m_values SET (gid_plus_1,gid_minus_1) = (rc_test_update_m_values(gid)); --doesn't work

Somebody now if this is possible?

CHeers,
Rémi-C

Re: update several columns from function returning several values

От
Tom Lane
Дата:
=?UTF-8?Q?R=C3=A9mi_Cura?= <remi.cura@gmail.com> writes:
> IF I define a function returning several values , I can't use it to update
> mutliple columns of a table at once.
> ...
> UPDATE test_update_m_values SET (gid_plus_1,gid_minus_1) =
> (rc_test_update_m_values(gid)); --doesn't work

> Somebody now if this is possible?

Not currently.  In 9.5 it'll be possible to do

UPDATE test_update_m_values SET (gid_plus_1,gid_minus_1) =
(select * from rc_test_update_m_values(gid));

but the syntax you were trying will never work, because it would be
ambiguous with the case of assigning a composite value to a single
composite column.

            regards, tom lane

Re: update several columns from function returning several values

От
Rémi Cura
Дата:
Thanks,
waiting for the 9.5 then =)
Cheers,
Rémi-C

2014-12-02 18:23 GMT+01:00 Tom Lane <tgl@sss.pgh.pa.us>:
Rémi Cura <remi.cura@gmail.com> writes:
> IF I define a function returning several values , I can't use it to update
> mutliple columns of a table at once.
> ...
> UPDATE test_update_m_values SET (gid_plus_1,gid_minus_1) =
> (rc_test_update_m_values(gid)); --doesn't work

> Somebody now if this is possible?

Not currently.  In 9.5 it'll be possible to do

UPDATE test_update_m_values SET (gid_plus_1,gid_minus_1) =
(select * from rc_test_update_m_values(gid));

but the syntax you were trying will never work, because it would be
ambiguous with the case of assigning a composite value to a single
composite column.

                        regards, tom lane