MySQL: select 来自相同 table 且名称相同的两列

Question

我正在创建一个应用程序来管理 game 和 team 数据。这是 mySQL 数据库结构：

CREATE TABLE team (
    id INT NOT NULL AUTO_INCREMENT,
    name VARCHAR(50) NOT NULL,
    PRIMARY KEY (id)
);

CREATE TABLE game (
    id INT NOT NULL AUTO_INCREMENT,
    id_team_A INT NOT NULL,
    id_team_B INT NOT NULL,
    PRIMARY KEY (id)
);

-- TEST VALUES: --

INSERT INTO team VALUES
    (1, "Barcelona"),
    (2, "Milan"),
    (3, "Real Madrid"),
    (4, "Inter");

INSERT INTO game VALUES
    (1, 1, 3),
    (2, 2, 4);

如您所见，每个 match 都有 2 个不同的 team 关联。

我正在尝试（但没有成功）获取单个查询比赛 ID、A 队名称、B 队名称。

首先我尝试了这样的查询：

SELECT game.id, team.name, team.name
FROM team INNER JOIN game
ON game.id_team_A = team.id;

但我的查询不关心 match.id_team_B 并且重复的 match.name 字段不会解决问题。

然后我开始使用 select 嵌套在一起的查询：

SELECT @g_id := game.id as id,
(SELECT team.name FROM team INNER JOIN game ON game.id_team_A = team.id WHERE game.id = @g_id) AS team_A,
(SELECT team.name FROM team INNER JOIN game ON game.id_team_B = team.id WHERE game.id = @g_id) AS team_B
FROM game;

终于得到了我想要的：

+-----+---------------+---------------+
| id  |    team_A     |    team_B     |
+-----+---------------+---------------+
|  1  |   Barcelona   |  Real Madrid  |
+-----+---------------+---------------+
|  2  |     Milan     |     Inter     |
+-----+---------------+---------------+

是否有easier/faster/cooler查询得到相同的结果？

注意：SQL Fiddle

Answer 1

您可以在相同的 table 之间进行连接，因此您可以这样做：

SELECT g.id as id, a.name as team_a, b.name as team_b 
FROM team a INNER JOIN game g ON g.id_team_A = a.id
INNER JOIN team b ON g.id_team_B = b.id

Answer 2

您需要两个别名：

SELECT g.id, t1.name team_A, t2.name team_B
FROM game g, team t1, team t2
WHERE g.id_team_A = t1.id AND g.id_team_B = t2.id

或加入：

SELECT g.id, t1.name team_A, t2.name team_B
FROM game g JOIN team t1 ON g.id_team_A = t1.id
JOIN team t2 ON g.id_team_B = t2.id

MySQL: select 来自相同 table 且名称相同的两列

MySQL: select two column from the same table with the same name

mysql

inner-join