基于ＳＱＬｓｅｒｖｅｒ的学生选课系统

十、 触发器练习 创建触发器，当Student表中的数据发生变化时（插入、更新、删除），自动修改Dept_age表中的数据（提示，需要两个触发器） （1）当在Student表中插入或修改学生信息时，在Dept_age更新或插入数据 CREATE TRIGGER trg_newage ON Student AFTER INSERT, UPDATE AS BEGIN UPDATE Dept_age SET Avg_age = ( SELECT AVG(Sage) FROM Student WHERE Student. Sdept = Dept_age. Sdept) WHERE Sdept IN ( SELECT Sdept FROM inserted ); INSERT INTO Dept_age (Sdept, Avg_age) SELECT Sdept, AVG(Sage) FROM Student WHERE Sdept IN ( SELECT Sdept FROM inserted ) AND Sdept NOT IN (SELECT Sdept FROM Dept_age) GROUP BY Sdept; END;