问印度铁路数据库在车站之间连接列车时出错

EN

SELECT trains.train_number, count(*) as "Number of schedules"
FROM trains
INNER JOIN train_schedule a USING (train_number) WHERE train_schedule.station_code = 'JU'
INNER JOIN train_schedule b USING (train_number) WHERE train_schedule.station_code = 'JP'

    SELECT distinct d1.train_no
      FROM train_schedule d1
INNER JOIN train_schedule d2 ON (     d2.train_no =  d1.train_no
                                  AND d2.stn_code <> d1.stn_code )
     WHERE d1.stn_code = 'JU'
       AND d2.stn_code = 'JP'
         ;