DML触发器(语句触发器)
由DML语句进行触发，当用户执行了INSERT,UPDATE,DELETE操作时就会触发操作
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DECLAREBEGIN -- 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 dbms_output.put_line(SQLERRM);END;
如果日期不对会提示：
ORA-20003: 在每个月的10号才允许办理入职和离职手续
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DECLAREBEGIN -- 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 dbms_output.put_line(SQLERRM);END;
结果如果是周末：
ORA-20003: 周末不允许更新myemp表ORA-06512: 在 "TESTS.CHANGEMYEMP_TRIGGER", line 7ORA-04088: 触发器 'TESTS.CHANGEMYEMP_TRIGGER' 执行过程中出错
平时下班时间:
ORA-20004: 在下班时间不允许更新myemp表ORA-06512: 在 "TESTS.CHANGEMYEMP_TRIGGER", line 9ORA-04088: 触发器 'TESTS.CHANGEMYEMP_TRIGGER' 执行过程中出错
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(v_myemp.comm,0); --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(v_myemp.empno,v_myemp.ename,v_myemp.sal,v_myemp.comm,v_myemptax); 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;