从2个REF'd列获取两个日期之间的差异

Question

我是SQL新手，我试图在两个REF'd列值之间获取2个值之间的日期。 我现在有表设置如下图所示：

CREATE OR REPLACE TYPE Person_Type AS OBJECT 
(PersonId NUMBER, 
DateBorn DATE) 

CREATE OR REPLACE TYPE Movie_Type AS OBJECT 
(MovieId NUMBER, 
ReleaseDate DATE) 

CREATE OR REPLACE TYPE Role_Type AS OBJECT 
(PersonId REF Person_Type, 
MovieId REF Movie_Type, 
Name VARCHAR2(40), 
MAP MEMBER FUNCTION Actor_Age RETURN NUMBER) 

插入数据是这样的：

INSERT INTO Person_Table 
VALUES (10000, '11-NOV-1974') 

INSERT INTO Movie_Table 
VALUES(1000000, '19-DEC-1997') 

INSERT INTO Role_Table 
VALUES((SELECT REF(a) FROM Person_Table a WHERE a.PersonId = 10000), 
(SELECT REF(b) FROM Movie_Table b WHERE b.MovieId = 1000000), 
'Some Person') 

我试图获得方法Actor_Age返回当天的区别有人出生，电影上映的日期。我已经试过以下，但它不会编译..

CREATE OR REPLACE TYPE BODY Role_Type 
AS 
    MAP MEMBER FUNCTION Actor_Age 
     RETURN NUMBER 
    IS 
    BEGIN 
    RETURN (MONTHS_BETWEEN((SELECT g.PersonId.DateBorn FROM Role_Table g), 
(SELECT f.MovieId.Releasedate FROM Role_Table f)/12)); 
    END; 
END; 

Answer 1

SQL Fiddle

的Oracle 11g R2架构设置：

CREATE OR REPLACE TYPE Person_Type AS OBJECT 
(PersonId NUMBER, 
DateBorn DATE) 
/

CREATE OR REPLACE TYPE Movie_Type AS OBJECT 
(MovieId NUMBER, 
ReleaseDate DATE) 
/

CREATE OR REPLACE TYPE Role_Type AS OBJECT 
(PersonId REF Person_Type, 
MovieId REF Movie_Type, 
Name VARCHAR2(40), 
MAP MEMBER FUNCTION Actor_Age RETURN NUMBER) 
/

CREATE OR REPLACE TYPE BODY Role_Type 
AS 
    MAP MEMBER FUNCTION Actor_Age 
    RETURN NUMBER 
    IS 
    p_age NUMBER; 
    BEGIN 
    SELECT MONTHS_BETWEEN(
      DEREF(MovieID).ReleaseDate, 
      DEREF(PersonID).DateBorn 
      )/12 
    INTO p_age 
    FROM DUAL; 
    RETURN p_age; 
    END; 
END; 
/

CREATE TABLE Person_Table OF Person_Type 
/
CREATE TABLE Movie_Table OF Movie_Type 
/
CREATE TABLE Role_Table OF Role_Type 
/

INSERT INTO Person_Table VALUES (10000, DATE '1970-01-01') 
/
INSERT INTO Movie_Table VALUES (1000000, DATE '2000-01-01') 
/
INSERT INTO Role_Table VALUES(
    (SELECT REF(a) FROM Person_Table a WHERE a.PersonId = 10000), 
    (SELECT REF(b) FROM Movie_Table b WHERE b.MovieId = 1000000), 
    'Some Person' 
) 
/

查询1：

SELECT Name, 
     r.Actor_Age() 
FROM Role_table r 

Results：

|  NAME | R.ACTOR_AGE() | 
|-------------|---------------| 
| Some Person |   30 | 

Answer 2

在PL SQL，你必须使用建设select into

CREATE OR REPLACE TYPE BODY Role_Type 
AS 
    MAP MEMBER FUNCTION Actor_Age 
     RETURN NUMBER 
    IS 
    v_date_born date ; 
    v_realse_date date ; 
    BEGIN 
    SELECT deref(self.PersonId).DateBorn into v_date_born FROM dual; 
    SELECT deref(self.MovieId).Releasedate into v_realse_date FROM dual; 
    RETURN (MONTHS_BETWEEN(v_date_born,v_realse_date)/12); 
    END; 
END;