Oracle触发器用法实例详解(2)

--创建映射表
CREATE TABLE dept_sal AS
SELECT deptno, COUNT(empno) total_emp, SUM(sal) total_sal
FROM scott.emp
GROUP BY deptno;
--创建触发器
CREATE OR REPLACE TRIGGER EMP_INFO
 AFTER INSERT OR UPDATE OR DELETE ON scott.EMP
DECLARE
 CURSOR CUR_EMP IS
  SELECT DEPTNO, COUNT(EMPNO) AS TOTAL_EMP, SUM(SAL) AS TOTAL_SAL FROM scott.EMP GROUP BY DEPTNO;
BEGIN
 DELETE DEPT_SAL; --触发时首先删除映射表信息
 FOR V_EMP IN CUR_EMP LOOP
  --DBMS_OUTPUT.PUT_LINE(v_emp.deptno || v_emp.total_emp || v_emp.total_sal);
  --插入数据
  INSERT INTO DEPT_SAL
  VALUES
  (V_EMP.DEPTNO, V_EMP.TOTAL_EMP, V_EMP.TOTAL_SAL);
 END LOOP;
END;
--对emp表进行DML操作
INSERT INTO emp(empno,deptno,sal) VALUES('123','10',10000);
SELECT * FROM dept_sal;
DELETE EMP WHERE empno=123;
SELECT * FROM dept_sal;

显示结果如下：

4)、创建触发器，用来记录表的删除数据

--创建表
CREATE TABLE employee(
  id  VARCHAR2(4) NOT NULL,
  name VARCHAR2(15) NOT NULL,
  age NUMBER(2)  NOT NULL,
  sex CHAR NOT NULL
);
--插入数据
INSERT INTO employee VALUES('e101','zhao',23,'M');
INSERT INTO employee VALUES('e102','jian',21,'F');
--创建记录表(包含数据记录)
CREATE TABLE old_employee AS SELECT * FROM employee;
--创建触发器
CREATE OR REPLACE TRIGGER TIG_OLD_EMP
 AFTER DELETE ON EMPLOYEE
 FOR EACH ROW --语句级触发，即每一行触发一次
BEGIN
 INSERT INTO OLD_EMPLOYEE VALUES (:OLD.ID, :OLD.NAME, :OLD.AGE, :OLD.SEX); --:old代表旧值
END;
/
--下面进行测试
DELETE employee;
SELECT * FROM old_employee;

5)、创建触发器，利用视图插入数据

--创建表
CREATE TABLE tab1 (tid NUMBER(4) PRIMARY KEY,tname VARCHAR2(20),tage NUMBER(2));
CREATE TABLE tab2 (tid NUMBER(4),ttel VARCHAR2(15),tadr VARCHAR2(30));
--插入数据
INSERT INTO tab1 VALUES(101,'zhao',22);
INSERT INTO tab1 VALUES(102,'yang',20);
INSERT INTO tab2 VALUES(101,'13761512841','AnHuiSuZhou');
INSERT INTO tab2 VALUES(102,'13563258514','AnHuiSuZhou');
--创建视图连接两张表
CREATE OR REPLACE VIEW tab_view AS SELECT tab1.tid,tname,ttel,tadr FROM tab1,tab2 WHERE tab1.tid = tab2.tid;
--创建触发器
CREATE OR REPLACE TRIGGER TAB_TRIGGER
 INSTEAD OF INSERT ON TAB_VIEW
BEGIN
 INSERT INTO TAB1 (TID, TNAME) VALUES (:NEW.TID, :NEW.TNAME);
 INSERT INTO TAB2 (TTEL, TADR) VALUES (:NEW.TTEL, :NEW.TADR);
END;
/
--现在就可以利用视图插入数据
INSERT INTO tab_view VALUES(106,'ljq','13886681288','beijing');
--查询
SELECT * FROM tab_view;
SELECT * FROM tab1;
SELECT * FROM tab2;

6)、创建触发器，比较emp表中更新的工资

--创建触发器
set serveroutput on;
CREATE OR REPLACE TRIGGER SAL_EMP
 BEFORE UPDATE ON EMP
 FOR EACH ROW
BEGIN
 IF :OLD.SAL > :NEW.SAL THEN
  DBMS_OUTPUT.PUT_LINE('工资减少');
 ELSIF :OLD.SAL < :NEW.SAL THEN
  DBMS_OUTPUT.PUT_LINE('工资增加');
 ELSE
  DBMS_OUTPUT.PUT_LINE('工资未作任何变动');
 END IF;
 DBMS_OUTPUT.PUT_LINE('更新前工资 ：' || :OLD.SAL);
 DBMS_OUTPUT.PUT_LINE('更新后工资 ：' || :NEW.SAL);
END;
/
--执行UPDATE查看效果
UPDATE emp SET sal = 3000 WHERE empno = '7788';

运行结果如下：

7)、创建触发器，将操作CREATE、DROP存储在log_info表

--创建表
CREATE TABLE log_info(
  manager_user VARCHAR2(15),
  manager_date VARCHAR2(15),
  manager_type VARCHAR2(15),
  obj_name  VARCHAR2(15),
  obj_type  VARCHAR2(15)
);
--创建触发器
set serveroutput on;
CREATE OR REPLACE TRIGGER TRIG_LOG_INFO
 AFTER CREATE OR DROP ON SCHEMA
BEGIN
 INSERT INTO LOG_INFO
 VALUES
  (USER,
  SYSDATE,
  SYS.DICTIONARY_OBJ_NAME,
  SYS.DICTIONARY_OBJ_OWNER,
  SYS.DICTIONARY_OBJ_TYPE);
END;
/
--测试语句
CREATE TABLE a(id NUMBER);
CREATE TYPE aa AS OBJECT(id NUMBER);
DROP TABLE a;
DROP TYPE aa;
--查看效果
SELECT * FROM log_info;
--相关数据字典-----------------------------------------------------
SELECT * FROM USER_TRIGGERS;
--必须以DBA身份登陆才能使用此数据字典
SELECT * FROM ALL_TRIGGERS;SELECT * FROM DBA_TRIGGERS;
--启用和禁用
ALTER TRIGGER trigger_name DISABLE;
ALTER TRIGGER trigger_name ENABLE;