如果两个'OR'条件都为真，则返回相同的行

我试图运行SQL查询以在竞争中显示一组打斗的结果。战斗细节存储在战斗机1，战斗机2和获胜者的字段中。我需要做的就是把在一起的所有战斗的列表，每个战斗在列表中出现两次 - 一次用，例如如果两个'OR'条件都为真，则返回相同的行

Competitor:fighter1, Opponent:fighter2, Winner:fighter1

而且，其他地方的列表

Competitor:fighter2, Opponent:fighter1, Winner:fighter1

我一直在使用一个sql union从每次打斗拉两次细节，并试图给战斗机1和战斗机2列分配不同的别名来交换它们，但我甚至不确定这是否可能。

我的查询是这样的（与其他表省略不必要的东西）

SELECT wp_ema_fights.fighter1 AS competitor, 
wp_ema_fights.fighter2 AS opponent, 
wp_ema_fights.winner AS winner 
FROM wp_ema_fights 
UNION ALL 
SELECT wp_ema_fights.fighter1 AS opponent, 
wp_ema_fights.fighter2 AS competitor, 
wp_ema_fights.winner AS winner 
FROM wp_ema_fights 
ORDER BY competitor

此查询显示各打了两次，但像这样：

Competitor:fighter1, Opponent:fighter2, Winner:fighter1 
Competitor:fighter1, Opponent:fighter2, Winner:fighter1

有没有人有任何想法如何我可以将两者交换，并根据每次战斗机被指定为“竞争对手”的顺序排列列表。

在此先感谢。

来源

2011-11-28 user10403

尝试：

SELECT wp_ema_fights.fighter1 AS competitor, 
     wp_ema_fights.fighter2 AS opponent, 
     wp_ema_fights.winner AS winner 
FROM  wp_ema_fights 
UNION ALL 
SELECT wp_ema_fights.fighter2 AS competitor, 
     wp_ema_fights.fighter1 AS opponent, 
     wp_ema_fights.winner AS winner 
FROM  wp_ema_fights 
ORDER BY competitor

来源

2011-11-28 14:03:33 Xophmeister

+1：不要移动SELECT语句中的字段，在***两个*** SELECT语句中将它们保持相同的顺序。 – MatBailie

非常感谢！这正在做我现在需要的。 – user10403

我认为UNION将忽略不匹配的列名，并根据它们在两个SELECT语句中出现的顺序排列列。

因此，只需在.fighter1和.fighter2之间调换第二个SELECT即可。

来源

2011-11-28 14:02:36 Alnitak

尝试：

SELECT wp_ema_fights.fighter1 AS competitor, 
wp_ema_fights.fighter2 AS opponent, 
wp_ema_fights.winner AS winner 
FROM wp_ema_fights 
UNION ALL 
SELECT wp_ema_fights.fighter2 AS competitor, 
wp_ema_fights.fighter1 AS opponent, 
wp_ema_fights.winner AS winner 
FROM wp_ema_fights 
ORDER BY competitor

来源

2011-11-28 14:06:53

除了Xophmester的回答，您可以用连接而不是UNION的做到这一点。这具有仅加载源数据一次而不是两次的优点。（这是非常大的数据集，而不仅仅是小的更有意义。）

SELECT CASE WHEN Mode.ID = 1 THEN wp_ema_fights.fighter1 ELSE wp_ema_fights.fighter2 END AS competitor, 
     CASE WHEN Mode.ID = 2 THEN wp_ema_fights.fighter2 ELSE wp_ema_fights.fighter1 END AS opponent, 
     wp_ema_fights.winner AS winner 
FROM  wp_ema_fights 
CROSS JOIN (SELECT 1 as ID UNION ALL SELECT 2 as ID) AS Mode 
ORDER BY CASE WHEN Mode.ID = 1 THEN wp_ema_fights.fighter1 ELSE wp_ema_fights.fighter2 END

来源

2011-11-28 14:09:36 MatBailie

如果你的SQL产品支持它，改变UNION ALL到UNION CORRESPONDING。

来源

2011-11-28 14:49:42 onedaywhen

如果两个'OR'条件都为真，则返回相同的行

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