oracle高级用法之触发器

/* 实施复杂的安全性检查：禁止在非工作时间插入员工 */

create or replace trigger securityemp

before insert

on emp

begin

 if to_char(sysdate,'day') in ('星期六','星期天') or

   to_number(to_char(sysdate,'hh24')) not between 9 and 18 then

   raise_application_error(-20001,'禁止在非工作时间插入新员工');

 end if;

end;

-- 删除触发器

drop trigger securityemp;

insert into emp (empno,ename,sal,deptno) values(1001,'libing',8000,10);

/* 数据的确认：涨后的薪水不能少于涨前的薪水 */

create or replace trigger checksalary

before update

on emp

for each row

begin

 if :new.sal < :old.sal then

   raise_application_error('20002','涨后的薪水不能少于涨前的薪水:||:new.sal||:old.sal');

 end if;

end;

update emp t set t.sal = t.sal -1 where t.ename = 'libing'; 

/* 数据的审计：涨后的工资超过6000，审计该员工 */ 

-- 创建审计表

create table audit_info(

information varchar2(200)

);

create or replace trigger do_audit_emp_salary

after update

on emp

for each row

begin

  if :new.sal > 6000 then

    insert into audit_info values(:new.empno||' '||:new.ename||' '||:new.sal);

  end if;

end;

update emp t set t.sal = t.sal + 1 where t.ename = 'libing';

commit;

select * from audit_info;

/* 实现数据的同步和备份:给员工涨完工资后，自动备份工资到备份表 */

-- 创建备份表

create table emp_back as select * from emp;

create or replace trigger sync_salary

after update

on emp

for each row

begin

  update emp_back set sal=:new.sal where empno =:new.empno;

end;

update emp set sal=sal+10 where empno=1001;