合并SQL中的相邻行？

我正在做一些基于员工工作时间的报告.在某些情况下,数据包含两个单独的记录,用于确切的单个时间块.

这是该表的基本版本和一些示例记录：

EmployeeID
StartTime
EndTime

数据：

EmpID      Start         End
----------------------------
#1001   10:00 AM    12:00 PM
#1001    4:00 PM     5:30 PM
#1001    5:30 PM     8:00 PM

在该示例中,最后两个记录在时间上是连续的.我想写一个组合任何相邻记录的查询,所以结果集是这样的：

EmpID      Start         End
----------------------------
#1001   10:00 AM    12:00 PM
#1001    4:00 PM     8:00 PM

理想情况下,它还应该能够处理2个以上的相邻记录,但这不是必需的.

解决方法

http://www.sqlmag.com/blog/puzzled-by-t-sql-blog-15/tsql/solutions-to-packing-date-and-time-intervals-puzzle-136851

这个似乎是最直接的：

WITH StartTimes AS
(
  SELECT DISTINCT username,starttime
  FROM dbo.Sessions AS S1
  WHERE NOT EXISTS
    (SELECT * FROM dbo.Sessions AS S2
     WHERE S2.username = S1.username
       AND S2.starttime < S1.starttime
       AND S2.endtime >= S1.starttime)
),EndTimes AS
(
  SELECT DISTINCT username,endtime
  FROM dbo.Sessions AS S1
  WHERE NOT EXISTS
    (SELECT * FROM dbo.Sessions AS S2
     WHERE S2.username = S1.username
       AND S2.endtime > S1.endtime
       AND S2.starttime <= S1.endtime)
)
SELECT username,starttime,(SELECT MIN(endtime) FROM EndTimes AS E
   WHERE E.username = S.username
     AND endtime >= starttime) AS endtime
FROM StartTimes AS S;

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