我有一张小桌子,这让我很难过:
Person datetime1 datetime2
Eric 2012-10-01 09:00:05.000 2012-10-01 22:00:00.000
Anna 2012-10-02 06:00:05.000 2012-10-03 12:00:05.000
Richard 2012-10-03 09:00:05.000 2012-10-04 02:00:05.000
Chuck 2012-10-01 12:00:05.000 2012-10-01 23:00:05.000
我正在尝试编写一个查询,它给了我统计表。此表包含有关用户何时登录和注销的信息(每日粒度):
Date logged_in logged_off
2012-10-01 2 2
2012-10-02 1 0
2012-10-03 1 1
2012-10-04 0 1
根据我的研究,枢轴命令可以解决问题吗?
select Person,
SUM(case when datetime1 = '2012-10-01' then 1 else 0 end) as [loggeed_in],
SUM(case when datetime2 = '2012-10-01' then 1 else 0 end) as [logged_of]
from table
group by Person
这不起作用......你有什么想法吗?