从Oracle中按函数返回的表中选择一列

Question

我有一个返回自定义对象表的函数。我希望从返回的结果中按名称选择某一列。

create or replace type sd_Serial_Number as object (
  serial_number VARCHAR2(32)
);

对象表

create or replace type sd_Serial_Number_Table as table of sd_Serial_Number;

功能

create function get_result
return sd_Serial_Number_Table as
    v_ret   sd_Serial_Number_Table;

begin
    select sd_Serial_Number(selected.SERIAL_NUMBER)
           bulk collect into v_ret
    from (
        selection here
        ) selected;

    return v_ret;
end get_result;

当我以这种方式调用函数时，我会得到一个名为 SERIAL_NUMBER 的单列的结果

select * from table(get_result());

但是，我不能这样做

select SERIAL_NUMBER from table(get_result());

有没有办法选择 SERIAL_NUMBER 列？

Answer 1

“我不能”很难调试。我会告诉你我可以（在你使用的同一个数据库版本上）。

SQL> SELECT * FROM v$version WHERE rownum = 1;

BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

---

SQL> CREATE OR REPLACE TYPE sd_serial_number AS OBJECT
  2  (
  3     serial_number VARCHAR2 (32)
  4  );
  5  /

Type created.

SQL> CREATE OR REPLACE TYPE sd_serial_number_table AS TABLE OF sd_serial_number;
  2  /

Type created.

SQL> CREATE OR REPLACE FUNCTION get_result
  2     RETURN sd_serial_number_table
  3  AS
  4     v_ret  sd_serial_number_table;
  5  BEGIN
  6     SELECT sd_serial_number (deptno)
  7       BULK COLLECT INTO v_ret
  8       FROM dept;
  9
 10     RETURN v_ret;
 11  END get_result;
 12  /

Function created.

测试：

SQL> SELECT * FROM TABLE (get_result ());

SERIAL_NUMBER
--------------------------------
10
20
30
40

SQL> SELECT serial_number FROM TABLE (get_result ());

SERIAL_NUMBER
--------------------------------
10
20
30
40

SQL>