如何查找具有最接近日期时间值的两个记录之间的日期差异，并且必须在同一组中进行比较

Question

如何查找具有最接近日期时间值的两个记录之间的日期差异，并且必须在同一组中进行比较？

示例数据如下：

Select * from tblGroup

Group      FinishedDatetime
1          03-01-2009 00:00
1          13-01-2009 22:00
1          08-01-2009 03:00
2          01-01-2009 10:00
2          13-01-2009 20:00
2          10:01-2009 10:00
3          27-10-2008 00:00
3          29-10-2008 00:00

预期产出：

Group      FinishedDatetime     Hours
1          03-01-2009 00:00     123 
1          13-01-2009 22:00     139
1          08-01-2009 03:00     117
2          01-01-2009 10:00     216
2          13-01-2009 20:00     82
2          10:01-2009 10:00     82
3          27-10-2008 00:00     48
3          29-10-2008 00:00     48

Answer 1

试试这个：

Select t1.[Group], DATEDIFF(HOUR, z.FinishedDatetime, t1.FinishedDatetime)
FROM tblGroup t1
OUTER APPLY(SELECT TOP 1 *
            FROM tblGroup t2 
            WHERE t2.[Group] = t1.[Group] AND t2.FinishedDatetime<t1.FinishedDatetime
            ORDER BY FinishedDatetime DESC)z