地铁路线查询sql

create proc Proc_SubwayZD
(
  @start varchar(50),
  @end varchar(50),
  @sc_id int
)
as
select sl_line_name from (
select ta.sl_id from((select * from SUBWAY_STATION where ss_station_name=@start) as ta
inner join (select * from SUBWAY_STATION where ss_station_name=@end) as tb
on ta.sl_id = tb.sl_id
)
group by ta.sl_id )as tc inner join SUBWAY_line as td on tc.sl_id = td.sl_id where td. sc_id=@sc_id