PostgreSQL触发器错误

Question

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();

当我尝试执行时:

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

********** B??d **********

ERROR: record "old" is not assigned yet
Stan SQL:55000
Szczegó?y:The tuple structure of a not-yet-assigned record is indeterminate.
Kontekst:PL/pgSQL function "aktualizujiloscpodan" line 11 at assignment

似乎它不知道是什么OLD或NEW.我该如何解决这个问题？

Answer 1

你需要使用 FOR EACH ROW

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

Answer 2

对于delete触发器,仅OLD定义记录并且NEW未定义.因此,在代码中,检查触发器是作为运行DELETE还是INSERT(变量TG_OP)并访问相应的记录.

此外,你可以在这里不计算在内,像这样:

CREATE OR REPLACE FUNCTION aktualizujIloscPodan() RETURNS TRIGGER AS
$BODY$ 
DECLARE 
    n integer;
BEGIN
    IF TG_OP = 'INSERT' then
       UPDATE "Studenci" SET "ilosc_podan" = "ilosc_podan" + 1 WHERE "ID"=NEW."studentID";
    ELSIF TG_OP = 'DELETE' then
       UPDATE "Studenci" SET "ilosc_podan" = "ilosc_podan" - 1 WHERE "ID"=OLD."studentID";

    END IF;
END;

$BODY$ 
LANGUAGE plpgsql;

DROP TRIGGER IF EXISTS triggenPodan ON "Podania";

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