将一个表中的多列连接到另一表中的单列

问题描述

我正在尝试学习如何将一个表中的多列连接到另一个表中的单列.

I'm trying to learn how to join multiple columns from one table to a single column from another table.

这是我最简单的表格结构:

团队

id | team_name |
1  |   teamA   |
2  |   teamB   |
3  |   teamC   |
4  |   teamD   |

交易

id |  team_1 (FK to teams.id)  |  team_2 (FK to teams.id)  |
1  |            1              |              2            |
2  |            3              |              4            |

这是我当前将trades.team_1 连接到teams.id 的SQL:

SELECT teams.team_name AS team1, teams.team_name AS team2, trades.team_1, trades.team_2
FROM teams
JOIN trades ON (trades.team_1 = teams.id);

我的问题是，如何创建第二个连接，同时将 trades.team_2 连接到 trades.id?

这意味着trades.team_1和trades.team_2都将加入trades.id

This would mean both trades.team_1 AND trades.team_2 would be joined to trades.id

我想要返回的结果是:

team1  |  team2  |  team_1  |  team_2  |
teamA  |  teamB  |    1     |     2    |
teamC  |  teamD  |    3     |     4    |

推荐答案

像这样:

select t1.team_name as team1, t2.team_name as team2, t.team_1, t.team_2
from trades t
inner join teams t1 on t1.id = t.team_1
inner join teams t2 on t2.id = t.team_2;

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