如果兩個'OR'條件都爲真，則返回相同的行

我試圖運行SQL查詢以在競爭中顯示一組打鬥的結果。戰鬥細節存儲在戰鬥機1，戰鬥機2和獲勝者的字段中。我需要做的就是把在一起的所有戰鬥的列表，每個戰鬥在列表中出現兩次 - 一次用，例如如果兩個'OR'條件都爲真，則返回相同的行

Competitor:fighter1, Opponent:fighter2, Winner:fighter1

而且，其他地方的列表

Competitor:fighter2, Opponent:fighter1, Winner:fighter1

我一直在使用一個sql union從每次打鬥拉兩次細節，並試圖給戰鬥機1和戰鬥機2列分配不同的別名來交換它們，但我甚至不確定這是否可能。

我的查詢是這樣的（與其他表省略不必要的東西）

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

此查詢顯示各打了兩次，但像這樣：

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

有沒有人有任何想法如何我可以將兩者交換，並根據每次戰鬥機被指定爲「競爭對手」的順序排列列表。

在此先感謝。

來源

2011-11-28 user10403

嘗試：

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

來源

2011-11-28 14:03:33 Xophmeister

+1：不要移動SELECT語句中的字段，在***兩個*** SELECT語句中將它們保持相同的順序。 – MatBailie

非常感謝！這正在做我現在需要的。 – user10403

我認爲UNION將忽略不匹配的列名，並根據它們在兩個SELECT語句中出現的順序排列列。

因此，只需在.fighter1和.fighter2之間調換第二個SELECT即可。

來源

2011-11-28 14:02:36 Alnitak

嘗試：

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

來源

2011-11-28 14:06:53

除了Xophmester的回答，您可以用連接而不是UNION的做到這一點。這具有僅加載源數據一次而不是兩次的優點。（這是非常大的數據集，而不僅僅是小的更有意義。）

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

來源

2011-11-28 14:09:36 MatBailie

如果你的SQL產品支持它，改變UNION ALL到UNION CORRESPONDING。

來源

2011-11-28 14:49:42 onedaywhen

如果兩個'OR'條件都爲真，則返回相同的行

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