基于同一表中的2个不同值获取计数

Question

我试图向用户提取游戏应用程序的统计信息，但需要帮助使其与使用多于一个查询的工作无关。

这是它的外观在很短的瞬间：用户ID（X INT），结果（胜和损失），种族（A，B和C）

我现在需要获取计数： 表赢和损失每个种族：

Select count(outcome) as win from games where userid = X and outcome = 'win' AND race = A 

Select count(outcome) as loss from games where userid = X and outcome = 'loss' AND race = A 

Select count(outcome) as win from games where userid = X and outcome = 'win' AND race = B 

Select count(outcome) as loss from games where userid = X and outcome = 'loss' AND race = B 

Select count(outcome) as win from games where userid = X and outcome = 'win' AND race = C 

Select count(outcome) as loss from games where userid = X and outcome = 'loss' AND race = C 

然后我基本上计算它们在PHP之后，但这是可笑缓慢的方式，当大量的游戏是在数据库中。

所以我基本上想有一个查询组种族是这样的：

赛| Win |损失

A_ _ ___X_ ___ _x

B_ _ ___X_ ___ _x

C_ _ ___X_ ___ _x

我是很新的更复杂的形式的SQL等优化任何建议此查询将是有益的。

谢谢。

Answer 1

SELECT race, 
     COUNT(CASE 
       WHEN outcome = 'win' THEN 1 
      END) AS win, 
     COUNT(CASE 
       WHEN outcome = 'loss' THEN 1 
      END) AS loss 
FROM games 
WHERE userid = X 
     AND race IN ('A', 'B', 'C') 
GROUP BY race