数据完整性：定义一个触发器，当删除Student表中数据时，先将删除的数据插入到另一个专门存放已删除的表中

SQL SERVER中实现: create trigger tri_del_stu on student for delete as begin insert into student_log select * from deleted end ORACLE中实现: create or replace trigger tri_del_stu before delete on student for each row begin insert into