十、 觸發(fā)器練習(xí) 創(chuàng)建觸發(fā)器，當(dāng)Student表中的數(shù)據(jù)發(fā)生變化時(shí)（插入、更新、刪除），自動(dòng)修改Dept_age表中的數(shù)據(jù)（提示，需要兩個(gè)觸發(fā)器） （1）當(dāng)在Student表中插入或修改學(xué)生信息時(shí)，在Dept_age更新或插入數(shù)據(jù) 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;