Question

我有两张名为＆＃39; club＆＃39;和＆＃39;时间表＆＃39;在数据库中。俱乐部的栏目是club_no，俱乐部和体育场。时间表有四列：match_no，team_one，team_two和date。

＆＃39; Match_no＆＃39;范围从1到56.＆＃39; team_one＆＃39;和＆＃39; team_two＆＃39;数字从1到8.这八个数字来自＆＃39; club_no＆＃39;表俱乐部中的专栏。

但是当我把这个查询放到零行时：

SELECT * FROM timetable
INNER JOIN clubs ON (
    timetable.team_one=clubs.club_no AND timetable.team_two=clubs.club_no
);

我想要的是一个包含如下列名称的表：Match_no，team_one，team_two和date。但是team_one和team_two这两个专栏应该被来自俱乐部的俱乐部名称所取代。表使用＆＃39; club_no＆＃39;这对每个俱乐部来说都是独一无二的。

另外，我在stackoverflow上尝试了几个关于这个主题的答案但没有帮助。它总是返回0行。

Answer 1

您无法在一次加入中执行此操作。您的ON子句正在查找 team_one和team_two等于club_no的行。因此，它等同于team_one=team_two，我假设你没有。{/ p>

您需要做的是为每个团队执行JOIN。

SELECT timetable.Match_no, timetable.date, club1.club AS team1, club2.club AS team2 FROM timetable INNER JOIN clubs AS club1 ON timetable.team_one = club1.club_no INNER JOIN clubs AS club2 ON timetable.team_two = club2.club_no;

Answer 2

你试过吗

SELECT C1.club, C2.club, T.Match_no, T.Date FROM timetable T 
INNER JOIN clubs C1 ON C1.club_no = T.team_one
INNER JOIN clubs C2 ON C2.club_no = T.team_two

Answer 3

我想你想要

select * from timetable
  inner join clubs on (timetable.team_once = clubs.club_no or timetable.team_two=clubs.club_no)

Answer 4

尝试将AND更改为OR

SELECT * FROM timetable t
JOIN clubs c ON t.team_one=c.club_no OR t.team_two=c.club_no;

或者您也可以加入每个团队，这可能是更好的解决方案

SELECT t.time, c.match_no, c.team_one, c1.team_two
FROM timetable t
JOIN clubs c ON t.team_one=c.club_no
JOIN clubs c1 ON t.team_two=c1.club_no

注意我为您的表添加了别名，因为当您有一个短表名时，它更容易阅读列

Answer 5

这是使用嵌套连接的一种解决方案。这有效但我觉得它不是最优化的解决方案。

select m_no, team1, clubs.club, date FROM 
    ( select timetable.match_no as m_no, clubs.club as team1, timetable.team_two as team2, timetable.date as date 
       FROM timetable INNER JOIN clubs ON timetable.team_one = clubs.club_no) T 
    INNER JOIN clubs ON T.team2=clubs.club_no

INNER JOIN有两列不能正常工作

5 个答案: