Question

我有一个表记录应用程序活动。每行包含一个DateTime（“Time”）和一个“EventType”列......（显然其他一些在这里并不重要）

我希望能够计算每小时发生的不同EventType的数量。

我目前正在获得单个EventType的基本计数：

select DATEADD(hh, (DATEDIFF(hh,0,Time)),0) as 'hour', count(*) as 'apploads' 
from PlaySessionEvent
where EventType = 0
Group By DATEADD(hh,(DATEDIFF(hh,0,Time)),0)
order by hour

扩展此功能以便在同一小时内计算多个不同的EventTypes的最简单方法是什么？

::更新

应该已经指定，我不仅仅按EventType分组，因为我只想要所有可用的EventType的子集。（即没有无聊的跟踪/调试数据）此外，我希望将不同的事件类型作为列，而不是复制DateTime条目的其他行。

...例如

DateTime           EventType1        EventType2
12:12:12 12/12/12  45                22

对不准确的初始问题抱歉！

Answer 1

select EventType, DATEADD(hh, (DATEDIFF(hh,0,Time)),0) as 'hour', count(*) as 'apploads'  
from PlaySessionEvent 
where EventType = 0 
Group By DATEADD(hh,(DATEDIFF(hh,0,Time)),0), EventType
order by hour

编辑：

更改问题的新解决方案：

select DATEADD(hh, (DATEDIFF(hh,0,Time)),0) as 'hour', count(*) as 'apploads', 
sum(case when EventType = 1 then 1 else 0 end) EventType1,
sum(case when EventType = 2 then 1 else 0 end) EventType2
from PlaySessionEvent 
where EventType = 0 
group By DATEDIFF(hh,0,Time)
order by hour

这是一种略有不同的写作方式：

select DATEADD(hh, (DATEDIFF(hh,0,Time)),0) as [hour], 
       COUNT(*) [apploads], 
       COUNT(case when EventType = 1 then 1 end) EventType1,
       COUNT(case when EventType = 2 then 1 end) EventType2
from PlaySessionEvent 
where EventType = 0 
group By DATEDIFF(hh,0,Time)
order by hour

选择从同一个表中按时间分组的多个计数

1 个答案: