oracle 11g中调用成员函数

Question

我有一种称为预算的类型，定义为

create type budget as object ( 
    year number,
    amount number,
    member function left_over (year in number) return number
)

身体：

create type body budget as
    member function left_over(year in number) return number is
    begin
        return amount;
    end left_over;
end;

和一个对象表

create table budget_table of budget;

如何使用成员函数返回金额？就像是：

select b.left_over(2010) from budget_table b;

谢谢

Answer 1

该方法不需要参数：

SQL> create or replace type budget as object (
  2      year number,
  3      amount number,
  4      member function left_over return number
  5  )
  6  /

Type created.

SQL> create or replace type body budget as
  2      member function left_over return number is
  3      begin
  4          return amount;
  5      end left_over;
  6  end;
  7  /

Type body created.

SQL> create table budget_table of budget;

Table created.

SQL> insert into budget_table values (budget(2010,99));

1 row created.

SQL> commit;

Commit complete.

SQL> select b.left_over() from budget_table b;

B.LEFT_OVER()
-------------
           99

（我认为这是一项学术练习，因为在真实的商业数据库中创建这样的表是没有意义的！）

限制特定年份的预算：

SQL> insert into budget_table values (budget(2010,99));

1 row created.
SQL> select b.left_over() from budget_table b;

B.LEFT_OVER()
-------------
           88
           99

SQL> select b.left_over() from budget_table b
  2  where b.year = 2010;

B.LEFT_OVER()
-------------
           99