plsql pipe

create or replace type Arr as table of varchar2(500);
create or replace function getApproverByRole2(busi_dept_id IN NUMBER,
                                role_code    IN VARCHAR2) RETURN Arr pipelined AS
  v_org_id NUMBER;
BEGIN
  begin
    select org_id
      into v_org_id
      from sys_dept_ sd
     where sd.id = busi_dept_id;
  exception
    when others then
      v_org_id := null;
  end;

    for person in (SELECT u.*
                        FROM sys_user_      u,
                             sys_role_      r,
                             sys_user_role_ ur,
                             sys_role_org_  rorg
                       WHERE u.id = ur.user_id
                         AND r.id = ur.role_id
                         AND r.id = rorg.role_id
                         AND r.role_code = role_code
                         AND rorg.org_id = v_org_id) loop
      pipe row(person.user_name);
    end loop;
  return;
END;

select column_value  from table(cast(getApproverByRole2(1456837,'APP_HR') as Arr ));