[PgSQL 7.4.1] Problem with subquery

Edwin Pauli <edwin@epauli.dyndns.org> writes:

There are troubles with a subquery after the upgrade.

SELECT team_naam, team_id, wpim, (
SELECT count(thuis_uitslag)
FROM wedstrijden
WHERE (thuis_wed = t.team_id
OR uit_wed = t.team_id)
AND seizoen_id = 3 AND klasse_id = 1)
AS wd, (
SELECT count(t.team_id)
FROM wedstrijden w
WHERE (thuis_wed = t.team_id AND thuis_uitslag >
uit_uitslag OR uit_wed = t.team_id
AND thuis_uitslag < uit_uitslag)
AND seizoen_id = 3
AND klasse_id = 1 )
AS gw
FROM teams t
WHERE seizoen_id = 3 AND klasse_id = 1
GROUP BY t.team_naam, t.team_id, t.team_id, t.wpim

ERROR: more than one row returned by a subquery used as an expression

Since t.team_id is a variable of the outer query, count(t.team_id) is an
aggregate of the outer query according to the SQL spec, and accordingly
it is just a constant from the perspective of your second sub-SELECT.
That sub-SELECT is therefore not doing any aggregation of its own and
is trying to return multiple rows.

We didn't implement this fine point per-spec before 7.4, but we do now.
See http://archives.postgresql.org/pgsql-hackers/2003-06/msg00070.php

Solution: use count(*) instead. AFAICS you have no need to check
whether t.team_id is nonnull, since the WHERE clause could not succeed
anyway if it's null.

regards, tom lane

Tom Lane wrote:

---------------------------(end of broadcast)---------------------------
TIP 6: Have you searched our list archives?
http://archives.postgresql.org

No. I'm searching in the archive now.
When i can't find a solution, i'll try your suggestion : count(*).

--
Edwin Pauli