oracle触发器的使用（二）

　　临回家了，把这两天搞的oracle的点东西，放到博客上，主要是触发器的使用，没有涉及到具体复杂的业务，但是都是比较实际的业务需求。实际中能够用的上，主要是用于审计，用户实际业务需求（友好性的考虑），与view等配合使用等。直接上code吧，在pl/sql中执行相应的模块就能得到相应的结果，注释和清晰，主要是看书一步步搞的。有的自己备用方便。如果有用，大家也可以看看。

--好的创建表的方法
DECLARE
  TB NUMBER;
BEGIN
  SELECT COUNT(*) INTO TB FROM TABS WHERE TABLE_NAME = 'FRAME';
  IF TB <> 0 THEN
    EXECUTE IMMEDIATE 'DROP TABLE frame';
    EXECUTE IMMEDIATE '
    CREATE TABLE frame
    (
       bowler_id number,
       game_id number,
       frame_id number,
       strike varchar2(1) default ''N'',
       spare varchar2(1) default ''N'',
       score number,
       constraint frame_pk
       primary key (bowler_id,game_id,frame_id)
    )';
    DBMS_OUTPUT.PUT_LINE('存在该表已删除，并创建新的表');
  ELSE
    EXECUTE IMMEDIATE 'CREATE TABLE frame
    (
       bowler_id number,
       game_id number,
       frame_id number,
       strike varchar2(1) default ''N'',
       spare varchar2(1) default ''N'',
       score number,
       constraint frame_pk
       primary key (bowler_id,game_id,frame_id)
    )';
    DBMS_OUTPUT.PUT_LINE('不存在该表，已创建新表');
  END IF;
END;

--创建审计表
DECLARE
  TB NUMBER;
BEGIN
  SELECT COUNT(*) INTO TB FROM TABS WHERE TABLE_NAME = 'FRAME_AUDIT';
  IF TB <> 0 THEN
    EXECUTE IMMEDIATE 'DROP TABLE frame_audit';
    EXECUTE IMMEDIATE '
    CREATE TABLE frame_audit
    (
           bowler_id NUMBER,
           game_id NUMBER,
           frame_id NUMBER,
           old_strike VARCHAR2(1),
           new_strike VARCHAR2(1),
           
           old_spare VARCHAR2(1),
           new_spare VARCHAR2(1),
           
           old_score number,
           new_score number,
           
           change_date DATE,
           operation VARCHAR2(6) 
    )';
    DBMS_OUTPUT.PUT_LINE('存在该表已删除，并创建新的表');
  ELSE
    EXECUTE IMMEDIATE 'CREATE TABLE frame_audit
                  (
                         bowler_id NUMBER,
                         game_id NUMBER,
                         frame_id NUMBER,
                         old_strike VARCHAR2(1),
                         new_strike VARCHAR2(1),
                         
                         old_spare VARCHAR2(1),
                         new_spare VARCHAR2(1),
                         
                         old_score number,
                         new_score number,
                         
                         change_date DATE,
                         operation VARCHAR2(6) 
                  )';
    DBMS_OUTPUT.PUT_LINE('不存在该表，已创建新表');
  END IF;
END;


--创建触发器
CREATE OR REPLACE TRIGGER audit_frames
AFTER INSERT OR UPDATE OR DELETE ON frame
FOR EACH ROW
  BEGIN
    IF inserting THEN
      INSERT INTO frame_audit(bowler_id,game_id,frame_id,
       new_strike,new_spare,
       new_score,change_date,operation)
      VALUES(:new.bowler_id,:new.game_id,:new.frame_id,:new.strike,:new.spare,:new.score,SYSDATE,'insert');
      
      ELSIF updating THEN
      INSERT INTO frame_audit(bowler_id,game_id,frame_id,
      old_strike,new_strike,old_spare,new_spare,
      old_score,new_score,change_date,operation)
      VALUES(:new.bowler_id,:new.game_id,:new.frame_id,:old.strike,:new.strike,:old.spare,:new.spare,:old.score,:new.score,SYSDATE,'update');
      
      ELSIF deleting THEN
      INSERT INTO frame_audit(bowler_id,game_id,frame_id,
       old_strike,old_spare,
       old_score,change_date,operation)
      VALUES(:old.bowler_id,:old.game_id,:old.frame_id,:old.strike,:old.spare,:old.score,SYSDATE,'insert');
      
      END IF;
      END audit_frames;

--在创建之后，后来使用的时候报了一个触发器无效且未通过认证的错误
--解决办法是找到触发器-》右键查看-》找到相应的错误（insert->inserting）.问题解决。


INSERT INTO frame (bowler_id,game_id,frame_id,strike)
VALUES (1,2,3,'y');


SELECT * FROM frame;

UPDATE frame SET strike ='N',
spare = 'y'
WHERE bowler_id =1
AND game_id =2
AND frame_id =3;

DELETE frame WHERE bowler_id = 1;

COMMIT;
SELECT * FROM frame;
SELECT * FROM frame_audit;

/*创建更加有针对性的触发器：只是在修改记录的时候触发*/
/*************Begin*****************/
CREATE OR REPLACE TRIGGER audit_update
AFTER UPDATE OF strike,spare ,score ON frame
REFERENCING OLD AS prior_to_cheat NEW AS after_cheat
FOR EACH ROW
  WHEN (
    prior_to_cheat.strike != after_cheat.strike
    OR prior_to_cheat.spare != after_cheat.spare
    OR prior_to_cheat.score != after_cheat.score)
    BEGIN 
      INSERT INTO frame_audit(bowler_id,game_id,frame_id,
      old_strike,new_strike,old_spare,new_spare,
      old_score,new_score,change_date,operation)
      VALUES(:prior_to_cheat.bowler_id,:prior_to_cheat.game_id,:prior_to_cheat.frame_id,:after_cheat.strike,:prior_to_cheat.strike,:after_cheat.spare,:prior_to_cheat.spare,:after_cheat.score,:prior_to_cheat.score,SYSDATE,'update');
    END;
--测试语句
INSERT INTO frame (bowler_id,game_id,frame_id,strike)
VALUES (1,1,1,'y');
UPDATE frame SET strike = strike;
SELECT * FROM frame;
SELECT * FROM frame_audit;
/********************END**************************/

/***********************************/
--增加有好性，在击球全中和2次全中的选手加10分
/***************BEGIN*****************/

CREATE OR REPLACE TRIGGER set_score
BEFORE INSERT ON frame
FOR EACH ROW
  WHEN (NEW.score IS NOT NULL)
    BEGIN
      IF :New.strike ='y' OR :new.spare = 'y'
        THEN 
          :new.score := :new.score+10;
      END IF;
  END;
      
--测试语句
INSERT INTO frame (bowler_id,game_id,frame_id,strike,score)
VALUES (2,2,1,'y',10);

INSERT INTO frame (bowler_id,game_id,frame_id,strike,score)
VALUES (2,2,2,'y',9);

INSERT INTO frame (bowler_id,game_id,frame_id,strike,score)
VALUES (3,1,1,'n',9);
SELECT * FROM frame;
SELECT * FROM frame_audit;
/*****************分数校验***********/
CREATE OR REPLACE TRIGGER validate_score
AFTER INSERT OR UPDATE ON frame
FOR EACH ROW
  BEGIN 
    IF :New.strike ='y' AND :new.score <10
      THEN 
        raise_application_error(-20001,'ERROR:score for strike must be >=10');
        ELSIF :new.spare ='y' AND :new.score<10
        THEN 
          raise_application_error(-20001,'ERROR:Score for spare must be >=10');
          ELSIF :new.strike ='y' AND :new.spare = 'y'
          THEN
            raise_application_error(-20001,'ERROR: Cannot Enter Spare and strike');
            
      END IF;
    END;
    --测试语句
INSERT INTO frame (bowler_id,game_id,frame_id,strike,score)
VALUES (5,1,1,'y',6);
 
SELECT * FROM frame;
SELECT * FROM frame_audit;       
/**************END********************/

/***********************************/
/**********************************/
/**********一个简单的快递系统******************/
/**********************************/
/********************************/
--如果表存在删除表让后再创建，不存在直接创建表
DECLARE
  I INTEGER;
BEGIN
  SELECT COUNT(*) INTO I FROM USER_TABLES WHERE TABLE_NAME = 'DELIVERY'; --注意表名大写
  IF I > 0 THEN
    DBMS_OUTPUT.PUT_LINE('该表已存在!删除后，创建表');
    EXECUTE IMMEDIATE 'DROP TABLE DELIVERY';
  ELSE
    DBMS_OUTPUT.PUT_LINE('该表不存在，创建表');
  END IF;
  EXECUTE IMMEDIATE 'CREATE TABLE delivery
                    (
                           delivery_id NUMBER,
                           delivery_start DATE,
                           delivery_end DATE,
                           area_id NUMBER,
                           driver_id NUMBER
                    )';
  END;       
--测试语句
  SELECT * FROM delivery;
--创建area表  
DECLARE
  I INTEGER;
BEGIN
  SELECT COUNT(*) INTO I FROM USER_TABLES WHERE TABLE_NAME = 'AREA'; --注意表名大写
  IF I > 0 THEN
    DBMS_OUTPUT.PUT_LINE('该表已存在!删除后，创建表');
    EXECUTE IMMEDIATE 'DROP TABLE AREA';
  ELSE
    DBMS_OUTPUT.PUT_LINE('该表不存在，创建表');
  END IF;
  EXECUTE IMMEDIATE 'CREATE TABLE area
                    (
                           area_id NUMBER,
                           area_desc varchar(30)
                    )';
END;  
--测试语句  
SELECT * FROM area;

--创建driver表
 DECLARE
  I INTEGER;
BEGIN
  SELECT COUNT(*) INTO I FROM USER_TABLES WHERE TABLE_NAME = 'DRIVER'; --注意表名大写
  IF I > 0 THEN
    DBMS_OUTPUT.PUT_LINE('该表已存在!删除后，创建表');
    EXECUTE IMMEDIATE 'DROP TABLE DRIVER';
  ELSE
    DBMS_OUTPUT.PUT_LINE('该表不存在，创建表');
  END IF;
  EXECUTE IMMEDIATE 'CREATE TABLE driver
                    (
                           driver_id NUMBER,
                           driver_name varchar2(30)
                    )';
END; 
--测试语句
SELECT * FROM driver; 

--创建3个序列为表提供唯一标识符
CREATE SEQUENCE delivery_id_seq;
CREATE SEQUENCE area_id_seq;
CREATE SEQUENCE driver_id_seq;

--用一个视图同时显示信息
CREATE OR REPLACE VIEW delivery_info AS
SELECT d.delivery_id,
       d.delivery_start,
       d.delivery_end,
       a.area_desc,
       dr.driver_name
        FROM delivery d ,area a,driver dr
        WHERE a.area_id = d.area_id
        AND dr.driver_id = d.driver_id;
        
--创建instead of insert 触发器
CREATE OR REPLACE TRIGGER delivery_info_insert
INSTEAD OF INSERT
ON delivery_info
DECLARE 
--cursour to get the driver by name
CURSOR curs_get_driver_id (cp_driver_name VARCHAR2)
IS 
SELECT driver_id
FROM
driver
WHERE driver_name = cp_driver_name;
v_driver_id NUMBER;
--cursor to get area by name
CURSOR curs_get_area_id (cp_area_desc VARCHAR2)
IS
SELECT area_id
FROM area
WHERE area_desc =cp_area_desc;

v_area_id NUMBER;
BEGIN
/*make sure the delivery_end value is null */  

IF :new.delivery_end IS NOT NULL
  THEN
    raise_application_error(-20000,'Delivery end date value must be null when delivery created');
END IF;

/*try to get the driver id by the name if not found
*then create a new brand driver id from the sequence 
**/
OPEN curs_get_driver_id(UPPER(:new.driver_name));

FETCH curs_get_driver_id INTO v_driver_id;

IF curs_get_driver_id %NOTFOUND
  THEN 
    SELECT driver_id_seq.nextval
    INTO v_driver_id
    FROM dual;
    
    INSERT INTO driver
    (
    driver_id,driver_name
    )
    VALUES (v_driver_id,UPPER(:new.driver_name));
END IF;

CLOSE curs_get_driver_id;
/*try to get the area id by the name if not found
*then create a new brand area id from the sequence
**/

OPEN curs_get_area_id(UPPER(:new.area_desc));

FETCH curs_get_area_id
INTO v_area_id;
IF curs_get_area_id %NOTFOUND
  THEN 
    SELECT area_id_seq.nextval
    INTO v_area_id
    FROM dual;
    
    INSERT INTO area
    (area_id ,area_desc)
    VALUES(v_area_id,UPPER(:new.area_desc));
END IF;

CLOSE curs_get_area_id;
/*create the delivery entry
*/
INSERT INTO delivery
(delivery_id,delivery_start,delivery_end,area_id,driver_id)
VALUES(delivery_id_seq.nextval,NVL(:new.delivery_start,SYSDATE),NULL,v_area_id,v_driver_id);

END;

/*************create instead of insert trigger end*******************************/

--测试语句
INSERT INTO delivery_info(delivery_id,
delivery_start,delivery_end,area_desc,driver_name)
VALUES (NULL,NULL,NULL,'local college','big ted');

SELECT * FROM delivery;
SELECT * FROM area;
SELECT * FROM driver;