鲁达 示例一、只有在每个月的10日才允许办理，新员工入职与离职，其他时间不允许增加和删除员工数据
--建立表
CREATE TABLE myemp AS SELECT * FROM emp;
--创建触发器
create or replace trigger changemyemp_trigger
before INSERT OR DELETE on myemp
DECLARE
v_curdate Varchar2(20);
BEGIN
SELECT to_char(SYSDATE,'dd') INTO v_curdate FROM dual;
IF trim(v_curdate)<>'10' THEN
Raise_application_error(-20003,'在每个月的10号才允许办理入职和离职手续');
END IF;
end changemyemp_trigger;
--向表中增加或者删除数据
DECLARE
BEGIN
-- INSERT INTO myemp(empno,ename,job,mgr,hiredate,sal,comm,deptno)VALUES(8888,'Test','CLERK',7369,SYSDATE,8000,NULL,10);
DELETE FROM myemp WHERE empno=7369;
EXCEPTION
WHEN OTHERS THEN
dbm(SQLERRM);
END;
示例二、周末及每天下班时间（每天9：00以前，18：00以后）不允许更新myemp表
--创建触发器
create or replace trigger changemyemp_trigger
before INSERT OR DELETE on myemp
declare
v_curhour Varchar2(20);
v_week VARCHAR2(20);
BEGIN
SELECT to_char(SYSDATE,'day'),to_char(SYSDATE,'hh24') INTO v_week,v_curhour FROM dual;
IF trim(v_week) IN('星期六','星期日') THEN
Raise_application_error(-20003,'周末不允许更新myemp表');
ELSIF TRIM(v_curhour)<'9'OR TRIM(v_curhour)>'18' THEN
Raise_application_error(-20004,'在下班时间不允许更新myemp表');
END IF;
end changemyemp_trigger;
--向表中增加或者删除数据
DECLARE
BEGIN
-- INSERT INTO myemp(empno,ename,job,mgr,hiredate,sal,comm,deptno)VALUES(8888,'Test','CLERK',7369,SYSDATE,8000,NULL,10);
DELETE FROM myemp WHERE empno=7369;
EXCEPTION
WHEN OTHERS THEN
dbm(SQLERRM);
END;
--示例三、每一个员工都在根基本工资收入缴税，2000以下3%，2000~5000，8%，5000以上10%，
--要求建立一张新的表来存放，员工编号，姓名，工资佣金，上缴的税，并且每次在修改员工表中的SAL和COMM字段后自动更新记录
--创建myemp_tax表
CREATE TABLE myemp_tax(
empno NUMBER(4),
ename VARCHAR2(10),
sal NUMBER(7,2),
comm NUMBER(7,2),
tax NUMBER(7,2),
CONSTRAINT pk_myempno PRIMARY KEY(empno),
CONSTRAINT fk_myempno FOREIGN KEY(empno) REFERENCES myemp(empno) ON DELETE CASCADE
);
--创建触发器
create or replace trigger myemp_out
after INSERT OR UPDATE OR DELETE on myemp
declare
PRAGMA AUTONOMOUS_TRANSACTION; --触发器自主事务
CURSOR cur_myemp IS SELECT * FROM myemp; --定义游标找到每行的记录
v_sal myemp.sal%TYPE; --定义变量计算收入
v_myemptax myemp_tax.tax%TYPE; --税收
v_myemp myemp%ROWTYPE;
BEGIN
DELETE FROM myemp_tax; --清空myemp_tax表;
FOR v_myemp IN cur_myemp LOOP
v_sal:=v_myemp.sal+nvl); --计算总工资
IF v_sal<2000 THEN
v_myemptax:=v_sal*0.03; --上缴税3%
ELSIF v_sal BETWEEN 2000 AND 5000 THEN
v_myemptax:=v_sal*0.08; --上缴税8%
ELSIF v_sal>5000 THEN
v_myemptax:=v_sal*0.1; --上缴税10%
END IF;
INSERT INTO myemp_tax(empno,ename,sal,comm,tax)
VALUES);
END LOOP;
COMMIT;
end myemp_out;
--向myemp表中增加一条的记录，然后查询myemp_tax表
INSERT INTO myemp(empno,ename,job,mgr,hiredate,sal,comm,deptno)VALUES(8898,'Test','CLERK',7369,SYSDATE,800,100,10);
SELECT * FROM myemp_tax;