如何根据MySQL中的两个不同条件从同一列中检索两个值？

Question

Table name: Route

Route_ID (int)
Route_From (int)
Route_To (int)

Table name: Stations

Station_ID (int),
Name (char)

Values of Route_From , Route_To , and Station_ID are the same.

I want to know how to retrieve two values from stations.name for two different conditions. For example, something like

 select s.name, s.name from stations s, route r, 
 where route_from=1 and
 route_to=3;

How do I do this?

Answer 1

Maybe you can do like this:

SELECT
    Route.Route_ID,
    fromStation.Name,
    toStation.Name
FROM
    Route
    LEFT JOIN Stations AS fromStation
        ON Route.Route_From =fromStation.Station_ID
    LEFT JOIN Stations AS toStation
        ON Route.Route_To  =toStation.Station_ID
WHERE 
    Route.Route_ID = 1;

Answer 2

I think you want something more like this:

select s1.name as route_from, s2.name as route_to from route r
left join stations s1 on r.route_from = s1.Station_ID
left join stations s2 on r.route_to = s2.Station_ID
where Route_ID = 1;

Answer 3

SELECT
Route.Route_ID,
fromStation.Name,
toStation.Name
FROM
Route
LEFT JOIN Stations AS fromStation
    ON Route.Route_From =fromStation.Station_ID
LEFT JOIN Stations AS toStation
    ON Route.Route_To  =toStation.Station_ID
WHERE 
Route.Route_ID = 1;