PostgreSQL触发器错误

我有：

CREATE OR REPLACE FUNCTION aktualizujIloscPodan() RETURNS TRIGGER AS
$BODY$
  DECLARE 
    n integer;
    sid integer;
BEGIN

sid=0;
IF (TG_OP='INSERT') THEN
sid = NEW."studentID";
ELSIF (TG_OP='DELETE') THEN
sid = OLD."studentID";
END IF;

n = COALESCE ((SELECT count("studentID") as c
FROM "Podania" WHERE "studentID"=sid
GROUP BY "studentID"),0);

UPDATE "Studenci" SET "licznikpodan" = n WHERE "ID"=sid;
END;
$BODY$
LANGUAGE plpgsql;

DROP TRIGGER IF EXISTS triggenPodan ON "Podania";

CREATE TRIGGER triggenPodan AFTER INSERT OR DELETE
ON "Podania"
EXECUTE PROCEDURE aktualizujIloscPodan();

当我尝试执行：

DELETE FROM "Podania"

I get

ERROR:  record "old" is not assigned yet
DETAIL:  The tuple structure of a not-yet-assigned record is indeterminate.
CONTEXT:  PL/pgsql function "aktualizujiloscpodan" line 11 at assignment

********** Błąd **********

ERROR: record "old" is not assigned yet
Stan sql:55000
Szczegóły:The tuple structure of a not-yet-assigned record is indeterminate.
Kontekst:PL/pgsql function "aktualizujiloscpodan" line 11 at assignment

好像不知道什么是OLD或NEW.我该如何解决？

您需要使用FOR EACH ROW

CREATE TRIGGER triggerPodan AFTER INSERT OR DELETE
ON "Podania" FOR EACH ROW
EXECUTE PROCEDURE aktualizujIloscPodan();