按日期分组时将整数行转换为列

Question

我有下表这些列TimeStamp [DateTime]，FromSysId [Int]，CrUSSDCnt [Int]

       TimeStamp           FromSysId          CrUSSDCnt
2015-06-18 18:58:15.380        25                 7
2015-06-18 19:45:17.130        21                 8
2015-06-18 20:43:18.920        22                 15
2015-06-18 21:34:33.090        25                 6
2015-06-18 22:55:33.317        22                 10

我希望将每个FromSysId显示为Column，同时计算每个FromSysId的CrUSSDCnt列并按小时分组TimeStime，如下所示：

       TimeStamp         Sys25   Sys22     Sys21       
2015-06-18 18:00:00       2        1         0
2015-06-18 19:00:00       4        6         3
2015-06-18 20:00:00       0        5         6
2015-06-18 21:00:00       0        7         2
2015-06-18 22:00:00       1        0         4

我尝试使用pivot或Joint，但我都没有像这样总结。 任何帮助。

Answer 1

这个问题的难点在于提取时间。这是一种方法：

select dateadd(hour, 0, datediff(hour, 0, timestamp)) as ToTheHour,
       sum(case when FromSysId = 25 then CrUSSDCnt else 0 end) as Sys25,
       sum(case when FromSysId = 22 then CrUSSDCnt else 0 end) as Sys22,
       sum(case when FromSysId = 21 then CrUSSDCnt else 0 end) as Sys21
from table t
group by dateadd(hour, 0, datediff(hour, 0, timestamp))
order by ToTheHour;

其余的只是条件聚合。