how to update hire date of employee by api

DECLARE
  x_warn_ee        VARCHAR2(1);
  p_effective_date DATE;

  CURSOR cur_people IS
    SELECT * FROM per_all_people_f;
BEGIN
  FOR rec_people IN cur_people LOOP
    BEGIN
      hr_change_start_date_api.update_start_date(p_validate         => FALSE,
                                                 p_person_id        => rec_people.person_id,
                                                 p_old_start_date   => rec_people.effective_start_date,
                                                 p_new_start_date   => to_date('2013/01/01',
                                                                               'yyyy/mm/dd'),
                                                 p_update_type      => 'E',
                                                 p_applicant_number => NULL,
                                                 p_warn_ee          => x_warn_ee);
    EXCEPTION
      WHEN OTHERS THEN
        dbms_output.put_line('person_id : ' || rec_people.person_id);
        dbms_output.put_line(SQLERRM);
        dbms_output.put_line('===============================');
    END;
  END LOOP;
END;
           

若员工之间从属关系：同时更新上属和下属时，更新上属时会报“ORA-20001: 此日期的分配主管不存在。”所以建议根据从属关系的层数N，执行上述过程N次。