我希望能够计算温度列超过特定温度的总时间(以分钟为单位)。例如，我想知道温度超过 16 度的分钟数。
如果读数在 12:28是16并阅读 12:30是17 ，我们是说来自 12:28至 12:30 , 值为 17 .
此外，如果第一个或唯一一个读数高于 x (17)，则这将是两分钟，因为设备启动后需要 x 分钟(在本例中为 2 分钟)才能获取第一个读数。
- SerialNumber 是读取温度的设备的序列号。
- CombinDateTime 是获取温度读数的时间。
- Temperature 是温度值。
SerialNumber, CombinDateTime, Temperature
1000649496, 2018-12-05 10:56:52, 16.6
1000649496, 2018-12-05 10:58:52, 17.3
1000649496, 2018-12-05 11:00:52, 16.8
1000649496, 2018-12-05 11:02:52, 16.6
1000649496, 2018-12-05 11:04:52, 16.4
1000649496, 2018-12-05 11:06:52, 16.3
1000649496, 2018-12-05 11:08:52, 16.3
1000649496, 2018-12-05 11:10:52, 16.2
1000649496, 2018-12-05 11:12:52, 16.2
1000649496, 2018-12-05 11:14:52, 16.2
1000649496, 2018-12-05 11:16:52, 16.2
1000649496, 2018-12-05 11:18:52, 16.2
1000649496, 2018-12-05 11:20:52, 16.1
1000649496, 2018-12-05 11:22:52, 16.1
1000649496, 2018-12-05 11:24:52, 16.1
1000649496, 2018-12-05 11:26:52, 16
1000649496, 2018-12-05 11:28:52, 16
1000649496, 2018-12-05 11:30:52, 16
1000649496, 2018-12-05 11:32:52, 16
1000649496, 2018-12-05 11:34:52, 16.1
1000649496, 2018-12-05 11:36:52, 16.1
1000649496, 2018-12-05 11:38:52, 16.1
1000649496, 2018-12-05 11:40:52, 16.1
1000649496, 2018-12-05 11:42:52, 16.1
1000649496, 2018-12-05 11:44:52, 16.1
1000649496, 2018-12-05 11:46:52, 16.1
1000649496, 2018-12-05 11:48:52, 16
1000649496, 2018-12-05 11:50:52, 16
1000649496, 2018-12-05 11:52:52, 16
1000649496, 2018-12-05 11:54:52, 16
1000649496, 2018-12-05 11:56:52, 16
1000649496, 2018-12-05 11:58:52, 16
1000649496, 2018-12-05 12:00:52, 16.1
1000649496, 2018-12-05 12:02:52, 16.1
1000649496, 2018-12-05 12:04:52, 16.1
1000649496, 2018-12-05 12:06:52, 16.1
1000649496, 2018-12-05 12:08:52, 16
1000649496, 2018-12-05 12:10:52, 16
1000649496, 2018-12-05 12:12:52, 16
1000649496, 2018-12-05 12:14:52, 16
1000649496, 2018-12-05 12:16:52, 16
1000649496, 2018-12-05 12:18:52, 16
1000649496, 2018-12-05 12:20:52, 16
1000649496, 2018-12-05 12:22:52, 16
1000649496, 2018-12-05 12:24:52, 16
1000649496, 2018-12-05 12:26:52, 16
1000649496, 2018-12-05 12:28:52, 16
1000649496, 2018-12-05 12:30:52, 16
1000649496, 2018-12-08 08:08:52, 15.1
1000649496, 2018-12-05 12:32:52, 16
1000649496, 2018-12-05 12:34:52, 16
1000649496, 2018-12-05 12:36:52, 16
1000649496, 2018-12-05 12:38:52, 16
到目前为止，我的查询非常基础:
SELECT SerialNumber, CombineDateTime, Temperature
FROM RawData
WHERE Temperature > 16
我想到的原则是我选择数据集和 order by date并遍历每一行，直到找到一个超过 16 的值.然后我获取日期，然后遍历记录，直到找到一个值为 <= 16 的值。 ，然后取该日期和时间以及datediff() minutes 期间.
我知道你不应该遍历 SQL记录，所以我正在考虑使用 CTE ，但我不太确定该怎么做。
例如，我的预期结果是:
SerialNumber, MinutesOver
1000649496, 1186
TIA
最佳答案
这看起来像是一个间隙和孤岛问题(连续 > 16 个温度和 <= 16 个温度需要分组在一起)，一种解决方案如下:
DECLARE @threshold DECIMAL(18, 2) = 16;
WITH cte1 AS (
SELECT *, CASE
-- first row itself is greater than threshold
WHEN Temperature > @threshold AND LAG(Temperature) OVER (PARTITION BY SerialNumber ORDER BY CombinDateTime) IS NULL THEN 1
-- next row is greater than threshold
WHEN Temperature <= @threshold AND LEAD(Temperature) OVER (PARTITION BY SerialNumber ORDER BY CombinDateTime) > @threshold THEN 1
-- prev row is greater than threshold
WHEN Temperature <= @threshold AND LAG(Temperature) OVER (PARTITION BY SerialNumber ORDER BY CombinDateTime) > @threshold THEN 1
END AS chg
FROM @t
), cte2 AS (
SELECT *, SUM(chg) OVER (PARTITION BY SerialNumber ORDER BY CombinDateTime) AS grp
FROM cte1
)
SELECT SerialNumber
, MIN(CombinDateTime) AS StartDateTime
, MAX(CombinDateTime) AS EndDateTime
, DATEDIFF(SECOND, MIN(CombinDateTime), MAX(CombinDateTime)) / 60.0 AS Total
FROM cte2
GROUP BY SerialNumber, grp
HAVING MAX(Temperature) > @threshold
结果:
SerialNumber StartDateTime EndDateTime Total
1000649496 2018-12-05 10:56:52 2018-12-05 11:24:52 28.000000
1000649496 2018-12-05 11:32:52 2018-12-05 11:46:52 14.000000
1000649496 2018-12-05 11:58:52 2018-12-05 12:06:52 8.000000
关于sql - 计算值大于 x 的时间(以分钟为单位)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/54476888/