Re: getting back autonumber just inserted

On Fri, Jul 08, 2005 at 12:26:30AM +0200, PFC wrote:
>
> >That's a different issue than whether currval() is subject to
> >interference from other transactions. And just wait until PostgreSQL
> >8.1 comes out and people start using lastval() -- then it could get
> >*really* confusing which sequence value you're getting.
>
> What happens if an INSERT trigger inserts something into another
> table which also has a sequence ?

Do you mean with lastval()? Here's what happens:

CREATE FUNCTION trigfunc() RETURNS trigger AS $$
BEGIN
INSERT INTO bar (x) VALUES (NEW.x);
RETURN NEW;
END;
$$ LANGUAGE plpgsql VOLATILE;

CREATE TABLE foo (id serial PRIMARY KEY, x integer);
CREATE TABLE bar (id serial PRIMARY KEY, x integer);

CREATE TRIGGER footrig BEFORE INSERT ON foo
FOR EACH ROW EXECUTE PROCEDURE trigfunc();

ALTER SEQUENCE bar_id_seq RESTART WITH 50;

INSERT INTO foo (x) VALUES (12345);

SELECT lastval();
lastval
---------
50
(1 row)

SELECT * FROM foo;
id | x
----+-------
1 | 12345
(1 row)

SELECT * FROM bar;
id | x
----+-------
50 | 12345
(1 row)

--
Michael Fuhr
http://www.fuhr.org/~mfuhr/