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;