Postgres從表行中選擇

Question

我有表團隊，其中包含這樣的列

team_id | name    | competition_id
--------+---------+------
 1      | name 1  | 10
 2      | name 2  | 10

而且我也有這個桌子固定裝置

fixture_id  | home_team_id | away_team_id | competition_id
    --------+--------------+--------------+--------------
     1      | 1            | 2            | 10
     2      | 2            | 1            | 10 

桌上固定裝置的主鍵是fixture_id，home_team_id，away_team_id和Competition_id。 home_team，away_team和比賽也是外鍵。

如何從固定裝置中選擇home_team_name，away_team_name。

Answer 1

您可以兩次加入“ teams表中的“ fixtures表-一次用於主隊，一次用於客隊：

SELECT  fixture_id, home.name, away.name
FROM    fixtures f
JOIN    teams home on home.team_id = f.home_team_id
JOIN    teams away on away.team_id = f.way_team_id