DB2插入触发后:
CREATE TRIGGER NEW_REVIEW
AFTER INSERT ON REVIEW
REFERENCING NEW AS N_ROW
FOR EACH ROW
UPDATE PRODUCT SET Rating = (
Select AVG(Rating)
from Review
where ProductName = N_ROW.ProductName
)
更新后:
CREATE TRIGGER NEW_REVIEW
AFTER UPDATE ON REVIEW
REFERENCING NEW AS N_ROW
FOR EACH ROW
UPDATE PRODUCT SET Rating = (
Select AVG(Rating)
from Review
where ProductName = N_ROW.ProductName
)
后删除:
CREATE TRIGGER NEW_REVIEW
AFTER DELETE ON REVIEW
REFERENCING OLD AS O_ROW
FOR EACH ROW
UPDATE PRODUCT SET Rating = (
Select AVG(Rating)
from Review
where ProductName = O_ROW.ProductName
)
,了解更多信息退房CREATE TRIGGER statement。
谢谢。 虽然不完全正确。 UPDATE的WHERE子句缺失。 – pmr 2009-07-08 14:56:48