sql在一个查询中获取总数和过滤计数

Question

我想知道每个团队中有10％以上的用户百分比。当前，这需要两个查询：

SELECT COUNT(*) as winners, team FROM users WHERE points > 10 GROUP BY team

SELECT COUNT(*) as total, team FROM users GROUP BY team

我可以一口气做到这一点吗？

winners, total, team
5, 16, A

Answer 1

尝试一下，它只是在不过滤where子句中的整个数据集的情况下使用。

SELECT COUNT(*) as total    
, SUM(case when points > 10 then 1 else 0 end) as winners
, team 
FROM users 
GROUP BY team

还可以：

SELECT COUNT(*) as total    
, COUNT(case when points > 10 then 1 else NULL end) as winners
, team 
FROM users 
GROUP BY team

Answer 2

您可以使用Case .. When检查特定行的points是否大于10，并相应地计数（使用Sum()）。

SELECT COUNT(*) as total, 
       SUM(CASE WHEN points > 10 THEN 1 ELSE 0 END) AS winners, 
       team 
FROM users 
GROUP BY team

---

在MySQL中，我们可以将其进一步缩短，因为Sum()函数可以将条件运算符/函数的结果简单地转换为0/1（分别为false / true）：

SELECT COUNT(*) as total, 
       SUM(points > 10) AS winners, 
       team 
FROM users 
GROUP BY team

Answer 3

您可以尝试以下方式

SELECT COUNT(*) as winners, 
team, (select count(*) from users) as total FROM users 
WHERE points > 10 GROUP BY team

或者您可以在以下情况下使用大小写

SELECT team, COUNT(*) as total , 
       count(CASE WHEN points > 10 THEN 1 end) AS winners  

FROM users 
GROUP BY team