Question

我有两张桌子：

# Match 
id, team1_id , team2_id
-----------------------
1, 10, 20
2, 10, 50



# Team 
id, team_name, team_country
---------------------------
10, team A , England
20, team B , France

我试图从Match表中获取两个团队信息的列表，我想要一些像：

Team A (England)  vs Team B (France)

我尝试了这个，但我得到了错误的团队信息，我的查询确实有些问题。

这是我的疑问：

  SELECT `match`.*,
  `t1`.`team_country` as team1_country,
  `t2`.`team_country` as team2_country
  FROM `match`,
  `team` t1 , `team` t2
  WHERE `match`.`team1_id` = `t1`.`id` and `match`.`team2_id` = `t2`.`id`

提前致谢！

Answer 1

我只是用postgres在我的testmachine上摆弄它。 SQL不应该是不同的：

lara=# create table match ( id serial primary key, team1 int, team2 int);
CREATE TABLE
lara=# create table teams ( id serial primary key, name text, country text);
CREATE TABLE
lara=# insert into match(id, team1, team2) values (1,1,2),(2,1,3),(3,2,1);
INSERT 0 3
lara=# select * from match;
 id | team1 | team2
----+-------+-------
  1 |     1 |     2
  2 |     1 |     3
  3 |     2 |     1
(3 rows)

lara=# insert into teams values (1, 't1', 'en');
INSERT 0 1
lara=# insert into teams values (2, 't2', 'de');
INSERT 0 1
lara=# insert into teams values (3, 't3', 'fr');
INSERT 0 1
lara=# select * from match m left join teams t1 on t1.id=m.team1 left join teams t2 on t2.id=m.team2;
 id | team1 | team2 | id | name | country | id | name | country
----+-------+-------+----+------+---------+----+------+---------
  1 |     1 |     2 |  1 | t1   | en      |  2 | t2   | de
  2 |     1 |     3 |  1 | t1   | en      |  3 | t3   | fr
  3 |     2 |     1 |  2 | t2   | de      |  1 | t1   | en

所以你的实际查询是正确的。一个更干净的将是以下：

SELECT * FROM match m 
LEFT JOIN teams t1 ON t1.id=m.team1 
LEFT JOIN teams t2 ON t2.id=m.team2;

但你的问题显然不是SQL。

加入2个表来获取2个相关记录Mysql PHP

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