oracle - 如何消除子类型依赖？

Question

在下面的示例中，我为每种to_str()子类型编写了一个set()函数和一个pls_integer过程。除了类型外，功能和步骤几乎相同。

如何在不放弃子类型提供的约束的情况下消除为新的子类型编写另一个to_str()和set()的需要？

像这样回落到varchar2

procedure set(list in varchar2, prefix in varchar2)

然后称它为

set(to_str(list), 'foos:')

听起来不太好，我仍然需要为每个子类型提供 to_str()。

我愿意接受各种不同的建议，因为我是Oracle新手，而Oracle的新功能几乎每天都会为我带来惊喜。

我正在运行11.2.0.1.0。

create table so1table (
  id number,
  data varchar(20)
);

create or replace package so1 as
  subtype foo_t is pls_integer range 0 .. 4 not null;
  type foolist is table of foo_t;
  procedure set(id_ in number, list in foolist default foolist(1));

  subtype bar_t is pls_integer range 5 .. 10 not null;
  type barlist is table of bar_t;
  procedure set(id_ in number, list in barlist default barlist(5));
end;
/
show errors

create or replace package body so1 as
  /* Do I have always to implement these very similar functions/procedures for
  every single type ? */
  function to_str(list in foolist) return varchar2 as
    str varchar2(32767);
  begin
    for i in list.first .. list.last loop
      str := str || ' ' || list(i);
    end loop;
    return str;
  end;

  function to_str(list in barlist) return varchar2 as
    str varchar2(32767);
  begin
    for i in list.first .. list.last loop
      str := str || ' ' || list(i);
    end loop;
    return str;
  end;

  procedure set(id_ in number, list in foolist default foolist(1)) as
    values_ constant varchar2(32767) := 'foos:' || to_str(list);
  begin
    insert into so1table (id, data) values (id_, values_);
  end;

  procedure set(id_ in number, list in barlist default barlist(5)) as
    values_ constant varchar2(32767) := 'bars:' || to_str(list);
  begin
    insert into so1table (id, data) values (id_, values_);
  end;
end;
/
show errors

begin
  so1.set(1, so1.foolist(0, 3));
  so1.set(2, so1.barlist(5, 7, 10));
end;
/

SQLPLUS> select * from so1table;

        ID DATA
---------- --------------------
         1 foos: 0 3
         2 bars: 5 7 10

Answer 1

create table so1table (
    id number,
    data varchar(20)
);


create or replace type parent_type as object
(
    v_number number,
    --Prefix probably belongs with a list, not an individual value.
    --For simplicity, I'm not adding another level to the objects.
    v_prefix varchar2(10)
) not instantiable not final;
/

create or replace type parentlist as table of parent_type;
/


create or replace type foo_type under parent_type
(
    constructor function foo_type(v_number number) return self as result
);
/

--The data must be stored as a NUMBER, since ADTs don't support
--PL/SQL specific data types.  The type safety is enforced by the
--conversion in the constructor.
create or replace type body foo_type is
    constructor function foo_type(v_number number) return self as result
    as
        subtype foo_subtype is pls_integer range 0 .. 4 not null;
        new_number foo_subtype := v_number;
    begin
        self.v_number := new_number;
        self.v_prefix := 'foos:';
        return;
    end;
end;
/

create or replace type foolist as table of foo_type;
/


create or replace type bar_type under parent_type
(
    constructor function bar_type(v_number number) return self as result
);
/

create or replace type body bar_type is
    constructor function bar_type(v_number number) return self as result
    as
        subtype bar_subtype is pls_integer range 5 .. 10 not null;
        new_number bar_subtype := v_number;
    begin
        self.v_number := new_number;
        self.v_prefix := 'bars:';
        return;
    end;
end;
/

create or replace type barlist as table of bar_type;
/



create or replace package so1 as
    procedure set(id_ in number, list in parentlist);
end;
/

create or replace package body so1 as

    function to_str(list in parentlist) return varchar2 as
        v_value VARCHAR2(32767);
    begin
        for i in list.first .. list.last loop
            if i = 1 then
                v_value := list(i).v_prefix;
            end if;
            v_value := v_value || ' ' || list(i).v_number;
        end loop;

        return v_value;
    end to_str;

    procedure set(id_ in number, list in parentlist) as
        values_ constant varchar2(32767) := to_str(list);
    begin
        insert into so1table (id, data) values (id_, values_);
    end set;
end so1;
/


begin
    --You probably don't want to mix foos and bars, but it is allowed. 
    so1.set(1, parentlist(foo_type(0), foo_type(3)));
    so1.set(2, parentlist(bar_type(5), bar_type(7), bar_type(10)));

    --These would generate "ORA-06502: PL/SQL: numeric or value error"
    --so1.set(1, parentlist(foo_type(5)));
    --so1.set(1, parentlist(bar_type(4)));

end;
/

select * from so1table;