用于计算另一个表中平均值的DB2触发器

DB2 AFTER INSERT触发器:

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
      )

删除后:

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
      )

退房 CREATE TRIGGER statement 更多信息。