一次查询为何返回这么多重复记录!!如果要计算一列 的和该怎么办呢??
SELECT e2.SectionId, e2.SectionDistance, d2.TrainSectionSequence
FROM E_Station AS a1,E_Station AS a2, R_TrainStation AS b, E_Train AS c, R_TrainSection AS d1, R_TrainSection AS d2, E_Section AS e1, E_Section AS e2
WHERE a2.StationName="广州北" And a1.StationName="广州东" And c.TrainName="K254" And c.TrainId=b.TrainId And d1.TrainId=c.TrainId And e1.SectionEnd=a2.StationId And d1.SectionId=e1.SectionId And d2.TrainId=c.TrainId And (d2.TrainSectionSequence Between 1 And (d1.TrainSectionSequence-1)) And e2.SectionId=d2.SectionId
ORDER BY d2.TrainSectionSequence;