第8章數(shù)據(jù)庫的安全和完整性約束(參考版)
2025-07-23 13:00本頁面
【正文】 規(guī)則 6 問題：與上面各題創(chuàng)建觸發(fā)器的范例有什么不同？如何實現(xiàn)？ Create trigger young_sailor_update After Insert on Sailors Referencing New as N For Each Statement Insert into YoungSailors(sid,name,age,rating) Select sid,name,age,rating From N Where 19 。 創(chuàng)建觸發(fā)器，對 Sailors表的 Update操作進行監(jiān)控，如果 Reserves表中有元組引用修改前的 sid值作為外鍵 ,回卷此修改操作。 Create trigger referential_integrity_check Update of sid,bid on Reserves Referencing NEW as N For Each Row Event Before When (not (exists(Select * From Sailors Where sid = ) and (exists(Select * From Boats Where bid = )) ) Rollback。 Create trigger sailors_delete After Delete on Sailors Referencing OLD as O For Each Row Event When (exists(Select * From Reserves Where sid = )) Delete From Reserves Where sid = 。 Crea
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