oracle 面向對象（2）

继承／覆盖／重载

--------------------------------------------------------
--对象的继承,注意：UNDER
DROP TYPE HUMAN
CREATE TYPE HUMAN AS OBJECT(
     NAME VARCHAR2(20),
     SEX VARCHAR2(1), -- M :MALE    F:FEMALE
     BIRTHDAY DATE
) NOT FINAL;

CREATE TYPE EMPLOYEE_TYPE UNDER HUMAN(
     EMP_NO VARCHAR2(20),
     DEPT_NO VARCHAR2(20),
     JOB_TITLE VARCHAR2(60)
)
----------------------------------------------------------
--下面体现 NOT FINAL 的作用：　
DROP TYPE HUMAN
DROP TYPE EMPLOYEE_TYPE
CREATE TYPE HUMAN AS OBJECT(
     NAME VARCHAR2(20),
     SEX VARCHAR2(1),
     BIRTHDAY DATE
)

CREATE TYPE EMPLOYEE_TYPE UNDER HUMAN(
     EMP_NO VARCHAR2(20),
     DEPT_NO VARCHAR2(20),
     JOB_TITLE VARCHAR2(60)
)

/*　
对象类型默认为 FINAL ,即不能派生子类．
由于HUMAN 没有加：NOT FINAL ，所以，它不能作为另一个类型的超类，
在创建EMPLOYEE_TYPE 的时候，产生一个错误：
PLS-00590: 正在尝试创建一个最终类型的子类型
*/

----------------------------------------------------------
-- 对象类型的方法也是可以继承的．
DROP TYPE EMPLOYEE_TYPE
DROP TYPE HUMAN

CREATE OR REPLACE TYPE HUMAN AS OBJECT(
     NAME VARCHAR2(20),
     SEX VARCHAR2(1),
     BIRTHDAY DATE,
    
     MEMBER FUNCTION GET_AGE RETURN NUMBER
) NOT FINAL;

CREATE OR REPLACE TYPE BODY HUMAN AS
     MEMBER FUNCTION GET_AGE RETURN NUMBER AS
         V_NUM NUMBER;
     BEGIN
       SELECT FLOOR(MONTHS_BETWEEN(SYSDATE,TO_DATE('20060601','YYYYMMDD'))) INTO V_NUM FROM DUAL;
    RETURN V_NUM;
     END;
END;

SELECT MONTHS_BETWEEN(SYSDATE,TO_DATE('20060601','YYYYMMDD')) FROM DUAL;

CREATE OR REPLACE TYPE EMPLOYEE_TYPE UNDER HUMAN(
     EMP_NO VARCHAR2(20),
     DEPT_NO VARCHAR2(20)
)

--存储过程　
SET SERVEROUT ON
DECLARE
     EMP1 EMPLOYEE_TYPE := EMPLOYEE_TYPE('xling','M',TO_DATE('20060601','YYYYMMDD'),'2060006','DPT0201');
BEGIN
   DBMS_OUTPUT.PUT_LINE(EMP1.GET_AGE());
END;

--表
DROP TABLE EMPLOYEE

CREATE TABLE EMPLOYEE(
     GUID NUMBER NOT NULL,
     EMP EMPLOYEE_TYPE
)

CREATE OR REPLACE TRIGGER EMPLOYEE_T_I1
BEFORE INSERT ON EMPLOYEE REFERENCING NEW AS NEW OLD AS OLD FOR EACH ROW
BEGIN
   :NEW.GUID := XLING_PKG_TOOLS.F_GET_NEXTVAL('EMPLOYEE');
END;

CREATE OR REPLACE TRIGGER EMPLOYEE_T_D1
BEFORE DELETE ON EMPLOYEE REFERENCING NEW AS NEW OLD AS OLD FOR EACH ROW
BEGIN
   XLING_PKG_TOOLS.P_DELETE_GUID(:OLD.GUID);
END;

INSERT INTO EMPLOYEE (EMP) VALUES (EMPLOYEE_TYPE('xling','M',TO_DATE('20060601','YYYYMMDD'),'2060006','DPT0201'));
INSERT INTO EMPLOYEE (EMP) VALUES (EMPLOYEE_TYPE('snow','F',TO_DATE('20000601','YYYYMMDD'),'2060001','DPT0301'));
INSERT INTO EMPLOYEE (EMP) VALUES (EMPLOYEE_TYPE('werewi','M',TO_DATE('20050601','YYYYMMDD'),'2060007','DPT0401'));

--提示错误：ORA-22905: 无法从非嵌套表项访问行
-- TABLE 子句只能用在嵌套表？意思上有点像
SELECT
     GUID,
     I.NAME,I.SEX,I.BIRTHDAY,I.GET_AGE(),I.DEPT_NO,I.EMP_NO
FROM
   EMPLOYEE E,
   TABLE(E.EMP)

--
SELECT GUID,
     E.EMP.NAME,E.EMP.SEX,E.EMP.BIRTHDAY,E.EMP.GET_AGE(),E.EMP.EMP_NO,E.EMP.DEPT_NO
FROM
EMPLOYEE E

----------------------------------------------------------------------------------------
--抽象类型，注意：NOT FINAL NOT INSTANTIABLE
DROP TABLE EMPLOYEE
DROP TYPE EMPLOYEE_TYPE

CREATE OR REPLACE TYPE HUMAN AS OBJECT(
     NAME VARCHAR2(20),
     SEX VARCHAR2(1),
     BIRTHDAY DATE,
    
     MEMBER FUNCTION GET_AGE RETURN NUMBER
) NOT FINAL NOT INSTANTIABLE

CREATE OR REPLACE TYPE BODY HUMAN AS
     MEMBER FUNCTION GET_AGE RETURN NUMBER AS
         V_NUM NUMBER;
     BEGIN
       SELECT FLOOR(MONTHS_BETWEEN(SYSDATE,TO_DATE('20060601','YYYYMMDD'))) INTO V_NUM FROM DUAL;
    RETURN V_NUM;
     END;
END;

/*
现在试图声明一个抽象类的实例，产生如下错误．
PLS-00713: 正在试图实例化一种 NOT INSTANTIABLE 的类型
*/
DECLARE
     AMAN HUMAN := HUMAN('xling','M',TO_DATE('20060601','YYYYMMMDD'));
BEGIN
   DBMS_OUTPUT.PUT_LINE(AMAN.GET_AGE());
END;

-------------------------------------------------------
--抽象方法：拥有抽象方法的类型必须为抽象类型，抽象方法不能有主体

/*
这样声明是不对的，因为具有抽象方法的对象类型必须是抽象类型
*/
CREATE OR REPLACE TYPE HUMAN AS OBJECT(
     NAME VARCHAR2(20),
     SEX VARCHAR2(1),
     BIRTHDAY DATE,
    
     NOT INSTANTIABLE MEMBER FUNCTION GET_AGE RETURN NUMBER
) NOT FINAL NOT INSTANTIABLE

--
DROP TYPE HUMAN

CREATE OR REPLACE TYPE HUMAN AS OBJECT(
     NAME VARCHAR2(20),
     SEX VARCHAR2(1),
     BIRTHDAY DATE,
    
     NOT INSTANTIABLE MEMBER FUNCTION GET_AGE RETURN NUMBER
) NOT FINAL NOT INSTANTIABLE

/*
抽象类型也不能有主体，如下会提示：
PLS-00632: NOT INSTANTIABLE 方法不能具有主体
*/
CREATE OR REPLACE TYPE BODY HUMAN AS
     NOT INSTANTIABLE MEMBER FUNCTION GET_AGE RETURN NUMBER AS
     BEGIN
       NULL;
     END;
END;
DROP TYPE BODY HUMAN

/*
只能为非 NOT INSTANTIABLE 的方法创建方法体
*/
DROP TYPE HUMAN

CREATE OR REPLACE TYPE HUMAN AS OBJECT(
     NAME VARCHAR2(20),
     SEX VARCHAR2(1),
     BIRTHDAY DATE,
    
     NOT INSTANTIABLE MEMBER FUNCTION GET_AGE RETURN NUMBER,
     MEMBER FUNCTION TT RETURN NUMBER
) NOT FINAL NOT INSTANTIABLE

CREATE OR REPLACE TYPE BODY HUMAN AS
     MEMBER FUNCTION TT RETURN NUMBER AS
         V_NUM NUMBER;
     BEGIN
       SELECT MONTHS_BETWEEN(SYSDATE,BIRTHDAY) INTO V_NUM FROM DUAL;
    RETURN V_NUM;
     END;
END;

/*
在子类里实现超类的抽象方法，注意：OVERRIDING
*/

CREATE OR REPLACE TYPE EMPLOYEE_TYPE UNDER HUMAN(
     EMP_NO VARCHAR2(20),
     DEPT_NO VARCHAR2(20),
    
     OVERRIDING MEMBER FUNCTION GET_AGE RETURN NUMBER
)

CREATE OR REPLACE TYPE BODY EMPLOYEE_TYPE AS
     OVERRIDING MEMBER FUNCTION GET_AGE RETURN NUMBER AS
       V_NUM NUMBER;
     BEGIN
       SELECT FLOOR(MONTHS_BETWEEN(SYSDATE,BIRTHDAY)/12) INTO V_NUM FROM DUAL;
    RETURN V_NUM;
     END;
END;

SET SERVEROUT ON
DECLARE
     EMP1 EMPLOYEE_TYPE:= EMPLOYEE_TYPE('xling','M',TO_DATE('19840601','YYYYMMDD'),'2060006','DPT0201');
BEGIN
   DBMS_OUTPUT.PUT_LINE(EMP1.GET_AGE());
END;

/*
覆盖并不限于 NOT INSTANTIABLE 方法，子类可以覆盖所有超类的方法，除非在超类的方法中用 FINAL 限制　
*/

DROP TYPE EMPLOYEE_TYPE
DROP TYPE HUMAN

CREATE OR REPLACE TYPE HUMAN AS OBJECT(
     NAME VARCHAR2(20),
     SEX VARCHAR2(1),
     BIRTHDAY DATE,
    
     FINAL MEMBER FUNCTION GET_AGE RETURN NUMBER
) NOT FINAL

CREATE OR REPLACE TYPE BODY HUMAN AS
     FINAL MEMBER FUNCTION GET_AGE RETURN NUMBER AS
        V_NUM NUMBER;
     BEGIN
       SELECT FLOOR(MONTHS_BETWEEN(SYSDATE,BIRTHDAY)/12) INTO V_NUM FROM DUAL;
    RETURN V_NUM;
     END;
END;

/*
这里试图覆盖掉超类里的 FINAL 方法,
提示错误：PLS-00637:无法覆盖FINAL 方法
*/

CREATE OR REPLACE TYPE EMPLOYEE_TYPE UNDER HUMAN(
     EMP_NO VARCHAR2(20),
     DEPT_NO VARCHAR2(20),
    
     OVERRIDING MEMBER FUNCTION GET_AGE RETURN NUMBER
)

---------------------------------------------------------------------------
--方法的重载
DROP TYPE EMPLOYEE_TYPE
DROP TYPE HUMAN

CREATE OR REPLACE TYPE HUMAN AS OBJECT(
     NAME VARCHAR2(20),
     SEX VARCHAR2(1),
     BIRTHDAY DATE,
    
     MEMBER FUNCTION GET_AGE RETURN NUMBER,
     MEMBER FUNCTION GET_AGE(I_END_DATE IN DATE) RETURN NUMBER
)

CREATE OR REPLACE TYPE BODY HUMAN AS
    
     MEMBER FUNCTION GET_AGE RETURN NUMBER AS
         V_NUM NUMBER;
     BEGIN
       SELECT FLOOR(MONTHS_BETWEEN(SYSDATE,BIRTHDAY)/12) INTO V_NUM FROM DUAL;
    RETURN V_NUM;
     END;
    
     MEMBER FUNCTION GET_AGE(I_END_DATE IN DATE) RETURN NUMBER AS
         V_NUM NUMBER;
     BEGIN
       SELECT FLOOR(MONTHS_BETWEEN(I_END_DATE,BIRTHDAY)/12) INTO V_NUM FROM DUAL;
    RETURN V_NUM;
     END;
END;

SET SERVEROUT ON
DECLARE
     V_HUMAN HUMAN := HUMAN('xling','M',TO_DATE('19830714','YYYYMMDD'));
BEGIN
   DBMS_OUTPUT.PUT_LINE('Method 1:' || V_HUMAN.GET_AGE());
   DBMS_OUTPUT.PUT_LINE('Method 2:' || V_HUMAN.GET_AGE(TO_DATE('20000101','YYYYMMDD')));
END;

--------------------------------------------------------------------------------------------
--将FINAL 对象对型改为可继承,CASCADE 选项指定应该如何处理从属对象及其数据，
ALTER TYPE HUMAN NOT FINAL CASCADE

CREATE OR REPLACE TYPE EMPLOYEE_TYPE UNDER HUMAN(
     EMP_NO VARCHAR2(20),
     DEPT_NO VARCHAR2(20)
)

SET SERVEROUT ON
DECLARE
     V_EMP EMPLOYEE_TYPE := EMPLOYEE_TYPE('xling','M',TO_DATE('18900714','YYYYMMDD'),'2060006','DPT0201');
BEGIN
   DBMS_OUTPUT.PUT_LINE('Method 1:' || V_EMP.GET_AGE());
   DBMS_OUTPUT.PUT_LINE('Method 2:' || V_EMP.GET_AGE(TO_DATE('20000101','YYYYMMDD')));
END;