在表格中查找缺少的时间间隔

Question

我有下表,其中包含来自几个不同设备的每15分钟读取的值:

ID   DeviceID   Date                    Value
----------------------------------------------
1    3          24.08.2011 00:00:00     0.51
2    3          24.08.2011 00:15:00     2.9
3    3          24.08.2011 00:30:00     0
4    3          24.08.2011 00:45:00     7.1
5    3          24.08.2011 01:00:00     1.05
6    3          24.08.2011 03:15:00     3.8

我想在给定月份的每个设备中查找表中的所有空白,其中没有条目.对于上表,结果应该是这样的:

DeviceID    StartDate               EndDate
-------------------------------------------------------
3           24.08.2011 01:00:00     24.08.2011 03:15:00

该表有大约35000个设备和1亿个条目.

这就是我的尝试; 它很慢,但返回我需要的东西.然而,除了它的速度之外,还有另一个问题:它只发现在给定月份内设备的最后一个条目的丢失间隔; 之后的任何内容都将被忽略,因此可能会错过额外的缺失值间隔.

SELECT
    t2.Date AS StartDate
    , t1.Date AS EndDate
FROM
    TestTable t1
    INNER JOIN TestTable t2 ON t1.DeviceID = t2.DeviceID
WHERE
    (t2.Date = (SELECT MAX(Date) FROM TestTable t3 WHERE t3.Date < t1.Date AND t3.DeviceID = t1.DeviceID)
        AND DATEDIFF(MINUTE, t2.Date, t1.Date) > 15)
    AND t1.DeviceID = @id
    AND DATEPART(YEAR, t1.Date) = @year AND DATEPART(MONTH, t1.Date) = @month

Answer 1

以下应该工作,并且不返回deviceid的单个记录.

这个的要点是

• 为每条记录添加一个rownumber,按顺序为每个记录排序Date并重新启动DeviceID.
• 与self联接以创建包含两个原始行组合的行的结果.每行的列之间的关系是rownumber(+1)和DeviceID.
• 仅保留相关Date时间超过15分钟的行.

SQL语句

;WITH t AS (
  SELECT  *, rn = ROW_NUMBER() OVER (PARTITION BY DeviceID ORDER BY Date)
  FROM    TestTable
)  
SELECT  t1.DeviceID, t1.Date, t2.Date
FROM    t t1
        INNER JOIN t t2 ON t2.DeviceID = t1.DeviceID AND t2.rn = t1.rn + 1
WHERE   DATEDIFF(MINUTE, t1.Date, t2.Date) > 15        

测试脚本

;WITH TestTable (ID, DeviceID, Date, Value) AS (
  SELECT 1, 3, '2011-08-24 00:00:00', 0.51 UNION ALL
  SELECT 2, 3, '2011-08-24 00:15:00', 2.9 UNION ALL
  SELECT 3, 3, '2011-08-24 00:30:00', 0 UNION ALL
  SELECT 4, 3, '2011-08-24 00:45:00', 7.1 UNION ALL
  SELECT 5, 3, '2011-08-24 01:00:00', 1.05 UNION ALL
  SELECT 6, 3, '2011-08-24 03:15:00', 3.8 
)
, t AS (
  SELECT  *, rn = ROW_NUMBER() OVER (PARTITION BY DeviceID ORDER BY Date)
  FROM    TestTable
)  
SELECT  t1.DeviceID, t1.Date, t2.Date
FROM    t t1
        INNER JOIN t t2 ON t2.DeviceID = t1.DeviceID AND t2.rn = t1.rn + 1
WHERE   DATEDIFF(MINUTE, t1.Date, t2.Date) > 15