Re: [SQL] function return multiply rows

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От Alvaro Herrera
Тема Re: [SQL] function return multiply rows
Дата
Msg-id 20020928004600.741e3e8f.alvherre@atentus.com
обсуждение исходный текст
Ответ на Re: [SQL] function return multiply rows  (Joe Conway <mail@joeconway.com>)
Список pgsql-general
En Fri, 27 Sep 2002 09:44:55 -0700
Joe Conway <mail@joeconway.com> escribió:

> Jeroen Olthof wrote:

> > vw_teams is a view but same problem when trying it on a single table
> > CREATE FUNCTION test() RETURNS SETOF vw_teams AS 'select * from vw_teams;'
> > LANGUAGE 'sql';
> >
> > SELECT test();
> >
> > results in
> >
> >    test
> > -----------
> >  137789256
> >  137789256
> > (2 rows)
>
> The capability to return composite types (multi-column rows) is limited in <=
> PostgreSQL 7.2.x. What you are seeing are pointers to the rows, not the rows
> themselves.

While you are using the old versions, I believe you can retrieve the
columns by calling them by name.  At least this works on 7.2:

create table vw_teams (a int, b int);
insert into vw_teams values (1, 2);
insert into vw_teams values (3, 4);
select a(test()), b(test());
 a | b
---+---
 1 | 2
 3 | 4
(2 rows)

I suspect the function is being evaluated twice for each row.  Maybe
there's a better way.

--
Alvaro Herrera (<alvherre[a]atentus.com>)
La web junta la gente porque no importa que clase de mutante sexual seas,
tienes millones de posibles parejas. Pon "buscar gente que tengan sexo con
ciervos incendiánse", y el computador dirá "especifique el tipo de ciervo"
(Jason Alexander)

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