oracle 嵌套查询

select dat.id,
  dat.voucher_id,
  dat.type,
  dat.state,
  dat.start_point,
  dat.start_floor,
  dat.end_point,
  dat.end_floor,
  dat.box_no,
  dat.node_str,
  dat.task_type
 from dis_agv_task dat
inner join (select dar.task_id, dar.car_id
              from (select dar.task_id, dar.car_id
                      from dis_agv_route dar
                     where dar.car_id = #{carId}
                     order by dar.created_time desc) dar
             where rownum = 1) dar
   on dat.id = dar.task_id
where dat.state = #{state}