Question

我正在研究样本铁路数据库。我被困在检索一些数据。表结构是

培训：

TrainId | TrainName | FromStationId | ToStationId | DeptTime | ArrivalTime
...
...

RouteDetail：

Id | TrainId | RouteOrder | FromStationId | ToStationId | TrackId
...
...

电台：

Id | name
...
...

现在我正在尝试检索这些数据，但我还没有成功。

TrainName | RouteOrder | FromStationName | ToStationName

非常感谢任何帮助

感谢。

Answer 1

像这样的东西。如果不是，您必须提供更多详细信息。

SELECT 
    T.TrainName
    , RD.RoutOrder
    , S1.name as FromStationName
    , S2.name as ToStationName
FROM Train T
  LEFT JOIN RouteDetail RD
    ON T.TrainId = RD.TrainId
  LEFT JOIN Station S1
    ON RD.FromStationId = S1.Id
  LEFT JOIN Station S2
    ON RD.ToStationId = S2.Id

Answer 2

select t.trainname, r.routeorder, sfrom.name as fromstationname, sto.name as tostationname
from train t
inner join routedetail r on r.trainid = t.trainid
left join station sfrom on sfrom.id = fromstationid
left join station sto on sto.id = tostationid

另一个表中同一个表的多列

2 个答案: