我必须计算足球队的净胜球。 基本上是: (goalsScoredAtHome + goalsScoredAway) - (goalsConciededAtHome + goalsConciededAway) 一切都保存在一张表中:
homeTeam | awayTeam | goalsHome | goalsAway
USA | Poland | 2 | 0
Poland | USA | 3 | 1
这是我的 4 个独立查询:
(select sum(goalsHome) as GoalsScoredHome from game where home = 'USA'
+
select sum(goalsAway) as GoalsScoredAway from game where away = 'USA')
-
(select sum(goalsAway) as GoalsConciededHome from game where home = 'USA'
+
select sum(goalsHome) as GoalsConciededAway from game where away = 'USA')
有什么方法可以在一次查询中完成吗?
最佳答案
您的查询的直接翻译使用条件聚合:
select (sum(case when home = 'USA' then goalsHome else 0 end) +
sum(case when away = 'USA' then goalsAway else 0 end)
) -
(sum(case when home = 'USA' then goalsAway else 0 end) +
sum(case when away = 'USA' then goalsHome else 0 end)
)
from game;
您可以将其简化为:
select (sum(case when home = 'USA' then goalsHome - goalsAway else 0 end) +
sum(case when away = 'USA' then goalsAway - goalsHome else 0 end)
)
from game;
关于mysql - 如何区分两个求和查询,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/23243023/