将3个SQL SELECT合并为一条语句

Question

我有3张桌子：

• 战队（id_team，名称，id_season）
• 季节（id_season，名称，nbr_teams）
• Teams_Stats（id_stats，id_game，id_team，胜利，失败，平局）

我有3个单独运行良好的查询：

SELECT T.name, count(TS.victory) as Wins
FROM Teams T
JOIN Seasons S ON T.id_season = S.id_season AND S.name = '2015'
LEFT JOIN Teams_Stats TS ON TS.id_team = T.id_team AND TS.victory = 1
GROUP BY T.name 
ORDER BY T.name

SELECT T.name, count(TS.defeat) as Losses
FROM Teams T
JOIN Seasons S ON T.id_season = S.id_season AND S.name = '2015'
LEFT JOIN Teams_Stats TS ON TS.id_team = T.id_team AND TS.defeat = 1
GROUP BY T.name 
ORDER BY T.name

SELECT T.name, count(TS.victory) as Draws
FROM Teams T
JOIN Seasons S ON T.id_season = S.id_season AND S.name = '2015'
LEFT JOIN Teams_Stats TS ON TS.id_team = T.id_team AND TS.draw = 1
GROUP BY T.name 
ORDER BY T.name

我想知道如何只用1个查询就能得到相同的结果。 我就是不明白吗？ 也许有人可以给点光...

我很感激

谢谢。

Answer 1

您可以使用条件聚合：

SELECT T.name, 
       sum(TS.victory=1) as Wins,
       sum(TS.defeat=1) as Losses,
       sum(TS.draw =1) as Draws
FROM Teams T
JOIN Seasons S ON T.id_season = S.id_season AND S.name = '2015'
LEFT JOIN Teams_Stats TS ON TS.id_team = T.id_team 
GROUP BY T.name 
ORDER BY T.name

在这里演示