如何在按日期分组时获取唯一名称的总和

Question

我正在使用oracle 10g，我有一个登录用户的表

created                userid
--------------------   ------
10-jul-2014 10:10:10   usr1
10-jul-2014 10:12:10   usr2
10-jul-2014 11:12:10   usr1
10-jul-2014 12:12:10   usr3
13-jul-2014 10:12:10   usr1
13-jul-2014 11:12:10   usr2

我正在寻找的输出是

created            count(userid)
-----------        ------------------
10-jul-2014        3 (3 unique users)
13-jul-2014        2 (2 unique users)

我提出的查询未按预期工作

select trunc(created) cr, userid  
from loggedinusers
group by trunc(created), userid
order by trunc(created) asc;

Answer 1

使用以下查询

select trunc(created) cr, count(distinct userid)
from loggedinusers 
group by trunc(created)
order by trunc(created) asc;

Answer 2

select trunc(created) cr, count(userid) as cnt
from loggedinusers   
group by trunc(created)
order by trunc(created) asc;