计算每天从数据库中玩游戏的用户数

Question

我有一个带有表格答案的小游戏数据库： 每个用户每天最多可以玩2次， 表格答案结构如下：

UID | ANSWER | DATE

我想查询一下每天至少播放一次的用户数量。 我做了类似的事情，但这不起作用。

SELECT Day(date) as n, 
       Dayname(date) as m, 
       uid,             
       COUNT(uid) as c 
FROM answers
WHERE Year(date) = '2012' 
GROUP BY uid HAVING count( * ) <=2 //COUNT user who played at least 2 times per day
GROUP BY n //group by day
ORDER BY n

我希望得到这样的结果：

Friday | 9-5-2012 | 1254

Saturday | 10-5-2012 | 1427 ...

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Answer 1

而不是两个group by子句，使用一个在一天分组的单词：

select  day(date) as d
,       month(date) as m
,       count(distinct uid) as c 
from    answers
where   year(date) = '2012' 
group by 
        day(date)
,       month(date)
having  count(*) > 1