Oracle 如何将一个ref游标分配给另一个ref游标，并将其返回给调用过程

SQL> create or replace procedure abc(ref_cur out sys_refcursor)
  2  as
  3  begin
  4  open ref_cur for select * from scott.emp;
  5  end abc;
  6  /

Procedure created.

SQL>
SQL>
SQL> create or replace procedure xyz(ref_cur out sys_refcursor)
  2  as
  3  p_out sys_refcursor;
  4  begin
  5  abc(p_out);
  6  ref_cur := p_out;
  7  end xyz;
  8  /

Procedure created.

SQL>
SQL> variable rc refcursor
SQL> exec xyz(:rc);

PL/SQL procedure successfully completed.

SQL> print rc

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7369 SMITH      CLERK           7902 17-DEC-80        800                    20
      7499 ALLEN      SALESMAN        7698 20-FEB-81       1600        300         30
      7521 WARD       SALESMAN        7698 22-FEB-81       1250        500         30
      7566 JONES      MANAGER         7839 02-APR-81       2975                    20
      7654 MARTIN     SALESMAN        7698 28-SEP-81       1250       1400         30
      7698 BLAKE      MANAGER         7839 01-MAY-81       2850                    30
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7788 SCOTT      ANALYST         7566 09-DEC-82       3000                    20
      7839 KING       PRESIDENT            17-NOV-81       5000                    10
      7844 TURNER     SALESMAN        7698 08-SEP-81       1500                    30
      7876 ADAMS      CLERK           7788 12-JAN-83       1100                    20
      7900 JAMES      CLERK           7698 03-DEC-81        950                    30
      7902 FORD       ANALYST         7566 03-DEC-81       3000                    20
      7934 MILLER     CLERK           7782 23-JAN-82       1300                    10

14 rows selected.