使用别名时查询结果显示两次？

Question

我有一个查询，我在MySQL中运行，它使用别名从同一列中获取信息两次（往返于airport表的目的地）。

`SELECT AirlineName AS 'Airline Name',
     airport1.AirportName AS 'Flying From',
     airport2.AirportName AS 'Flying To',
     StopType AS 'Number of Stops'
FROM flightjunction
INNER JOIN airline ON flightjunction.FlightAirline = airline.AirlineID
INNER JOIN airport AS airport1 ON flightjunction.FlightFrom = airport1.AirportID
INNER JOIN airport AS airport2 ON flightjunction.FlightTo = airport2.AirportID
INNER JOIN stops ON flightjunction.FlightStops = stops.StopID;`

但是，我发现在运行此查询时会出现重复的结果。我哪里错了？提前感谢您的帮助！

Answer 1

由于在这种情况下你在同一个表上有两次内连接，你应该添加一个DISTINCT以消除重复。