trigger oracle

--实例1------------------------
--创建触发器，当用户对test表执行DML语句时，将相关信息记录到日志表
--创建测试表
CREATE TABLE test
(
t_id   NUMBER(4),
t_name VARCHAR2(20),
t_age NUMBER(2),
t_sex CHAR
);
--创建记录测试表
CREATE TABLE test_log
(
l_user   VARCHAR2(15),
l_type   VARCHAR2(15),
l_date   VARCHAR2(30)
);
--创建触发器
CREATE OR REPLACE TRIGGER test_trigger
AFTER DELETE OR INSERT OR UPDATE ON test
DECLARE
v_type test_log.l_type%TYPE;
BEGIN
IF INSERTING THEN --INSERT触发
v_type := 'INSERT';
DBMS_OUTPUT.PUT_LINE('记录已经成功插入，并已记录到日志');
ELSIF UPDATING THEN --UPDATE触发
v_type := 'UPDATE';
DBMS_OUTPUT.PUT_LINE('记录已经成功更新，并已记录到日志');
ELSIF DELETING THEN
v_type := 'DELETE';
DBMS_OUTPUT.PUT_LINE('记录已经成功删除，并已记录到日志');
END IF;
INSERT INTO test_log VALUES(user,v_type,
        TO_CHAR(sysdate,'yyyy-mm-dd hh24:mi:ss'));
END;
/
--下面我们来分别执行DML语句
INSERT INTO test VALUES(101,'zhao',22,'M');
UPDATE test SET t_age = 30 WHERE t_id = 101;
DELETE test WHERE t_id = 101;
--然后查看效果
SELECT * FROM test;
SELECT * FROM test_log;
--实例2------------------------
--创建触发器，它将映射emp表中每个部门的总人数和总工资
--创建映射表
CREATE TABLE dept_sal
AS
SELECT deptno,COUNT(empno) AS total_emp,SUM(sal) AS total_sal FROM emp GROUP BY deptno;
DESC dept_sal;
--创建触发器
CREATE OR REPLACE TRIGGER emp_info
AFTER INSERT OR UPDATE OR DELETE ON emp
DECLARE
CURSOR cur_emp IS
   SELECT deptno,COUNT(empno) AS total_emp,SUM(sal) AS total_sal FROM 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;
--实例3------------------------
--创建触发器，它记录表的删除数据
--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
);
DESC employee;
--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
CREATE TABLE old_employee AS
SELECT * FROM employee;
DESC old_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;
--实例4------------------------
--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 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(105,'zhaoyang','13886681288','beijing');
--查看效果
SELECT * FROM tab_view;
--实例5------------------------
--创建触发器，比较emp表中更新的工资
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';
--实例6------------------------
--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
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;
SELECT * FROM ALL_TRIGGERS;
SELECT * FROM DBA_TRIGGERS; --必须以DBA身份登陆才能使用此数据字典
--启用和禁用
ALTER TRIGGER trigger_name DISABLE;
ALTER TRIGGER trigger_name ENABLE;