十、 觸發器練習 創建觸發器，當Student表中的數據發生變化時（插入、更新、刪除），自動修改Dept_age表中的數據（提示，需要兩個觸發器） （1）當在Student表中插入或修改學生信息時，在Dept_age更新或插入數據 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;