sql - 在表中查找缺失的时间间隔

Question

我有下表，其中包含每 15 分钟从几个不同设备读取的值:

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

对于给定的月份，我想在没有条目的每个设备的表中找到所有空白。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

该表大约有 35000 个设备和 1 亿个条目。

这是我尝试过的；它相当慢，但返回了我需要的东西。然而，除了它的速度之外，还有另一个问题:它只能找到给定月份设备的最后一个条目的缺失间隔；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区间。

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

以下应该可以工作，并且不会只返回一个 deviceid 的单个记录。

这样做的要点是

为每条记录添加一个行号，按 Date 排序并为每个 DeviceID 重新启动.

与 self 连接以创建由两个原始行组合组成的行的结果。每行的列之间的关系是行号(+1)和DeviceID .

只保留相关 Date 的那些行超过15分钟。

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