sql - 按凌晨 4 点到凌晨 4 点的值分组 SQL Server

Question

我有从 04/01/2012 00:00 到 05/01/2012 05:00 的数据

让我们说

StartDate              Value 
04/01/2012 00:00       10 
04/01/2012 05:00       10 
04/01/2012 08:00       10

05/01/2012 01:00       10
05/01/2012 04:00       10
05/01/2012 05:00       10

如果我按日期分组

SUM(Value)...
GROUP BY YEAR(StartDate), MONTH(StartDate),DAY(StartDate)

这组数据从 04/01/2012 00:00 到 05/01/2012 00:00 并将全天值相加，即 30

但我需要按不同的时间分组

即 04/01/2012 04:00 到 05/01/2012 04:00 结果为 40

如何实现。以前有人这样做过...

Answer 1

SUM(Value)
...
GROUP BY CAST(DATEADD(hour, -4, MyDateCol) AS Date)