SQL 列出值大于特定值的周期

Question

我有一个 table 这样的 Id、DateTime、Device、Value。我需要找到 Value >=5 和 Return 这段时间的 From 和 To dateTime 的所有时间段。该设备可以是一个温度传感器，我需要一个 From/To 列表，其中温度已经超过 5。

如果我们认为它是一个温度传感器并且它每 5 分钟记录一次。 table 将是这样的：

Id DateTime         Device Value
--------------------------------
1  2015.09.01 09:10  T1     3,2 
2  2015.09.01 09:15  T1     5,2 
3  2015.09.01 09:20  T1     6,2 
4  2015.09.01 09:25  T1     5,8 
5  2015.09.01 09:30  T1     3,2 
6  2015.09.01 09:35  T1     1,2 
7  2015.09.01 09:40  T1     5,6 
8  2015.09.01 09:45  T1     6,1 
9  2015.09.01 09:50  T1     5,0 
10 2015.09.01 09:55  T1     2,0

我试图找到的时间段是从 09:15 到 09:25 以及从 09:40 到 09:50。

在 SQL Server 2014 中是否有一种聪明的方法可以做到这一点？

Answer 1

是的，有一种聪明的方法可以做到这一点。

看看 'PARTITION BY' 和 'OVER' 子句。

使用这些功能，我相信您应该能够按时间段对数据进行分区（分组）并获取每个组的 DateTime 列的 MIN 和 MAX 值。

Answer 2

这是获得所需结果的一种方式：

SELECT MIN([DateTime]) AS StartPeriod, MAX([DateTime]) AS EndPeriod,
       Device
FROM (       
SELECT Id, [DateTime], Device, Value,
       ROW_NUMBER() OVER (PARTITION BY Device ORDER BY Id) -
       COUNT(CASE WHEN Value >= 5 THEN 1 END) 
       OVER (PARTITION BY Device ORDER BY Id) AS grp
FROM mytable ) AS t
WHERE t.Value >= 5
GROUP BY Device, grp

如果您想每天获得 Start - End 个经期，您可能需要 PARTITION BY Device, [DateTime]。

Demo here

Answer 3

这基本上是 answered before，诀窍是您已经连续连续地订购了 id 列。如果那不存在，您需要做更多的前期工作才能使减法正常工作。

select * into #tempTable from (
select Id = 1,[DateTime] = cast('2015.09.01 09:10' as datetime), device = 'T1', value = 3.2
union all select 2,cast('2015.09.01 09:15' as datetime),'T1',5.2
union all select 3,cast('2015.09.01 09:20' as datetime),'T1',6.2
union all select 4,cast('2015.09.01 09:25' as datetime),'T1',5.8
union all select 5,cast('2015.09.01 09:30' as datetime),'T1',3.2
union all select 6,cast('2015.09.01 09:35' as datetime),'T1',1.2
union all select 7,cast('2015.09.01 09:40' as datetime),'T1',5.6
union all select 8,cast('2015.09.01 09:45' as datetime),'T1',6.1
union all select 9,cast('2015.09.01 09:50' as datetime),'T1',5
union all select 10,cast('2015.09.01 09:55' as datetime),'T1',2) A


with T as (select *, row_number() over (order by id) - id as grp
    from #tempTable
    where value >=5
    )
select [to] = min(T.Datetime), [from] =  max(T.DateTime) 
from T
group by T.grp
order by T.grp

输出为

to                        from
2015-09-01 09:40:00.000   2015-09-01 09:50:00.000
2015-09-01 09:15:00.000   2015-09-01 09:25:00.000

（我必须进行一些转换才能使您的 number/date 格式适合我）

Answer 4

我一直在使用 table 用户定义函数，该函数将请求的日期作为参数，函数内的游标允许填充返回的 table，如下所示：

CREATE TABLE sensor (id int not null identity(1,1) primary key, 
    measureDate datetime, sensor nvarchar(10), measure float)

INSERT sensor (measureDate, sensor, measure) VALUES
('2015-09-01 09:10', 'T1', '3.2'), ('2015-09-01 09:15', 'T1', '5.2'),
('2015-09-01 09:20', 'T1', '6.2'), ('2015-09-01 09:25', 'T1', '5.8'),
('2015-09-01 09:30', 'T1', '3.2'), ('2015-09-01 09:35', 'T1', '1.2'),
('2015-09-01 09:40', 'T1', '5.6'), ('2015-09-01 09:45', 'T1', '6.1'),
('2015-09-01 09:50', 'T1', '5.0'), ('2015-09-01 09:55', 'T1', '2.0')
GO
CREATE FUNCTION [dbo].[getTimeSpansBelowMaxTemp] (@measureDate date) 
    RETURNS @timeSpans TABLE (fromTime time, toTime time) AS BEGIN

    DECLARE @measure float, @currentMeasure float = NULL
    DECLARE @measureTime time, @fromMeasureTime time, @toMeasureTime time
    DECLARE yourCursor CURSOR FOR
    SELECT CAST(measureDate AS time), measure 
        FROM sensor
            WHERE CAST(measureDate as date) = @measureDate
    OPEN yourCursor
    FETCH NEXT FROM yourCursor INTO @measureTime, @measure
    WHILE (@@FETCH_STATUS = 0) BEGIN -- Loops on all the measures of the given day
        IF @measure >= 5.0 BEGIN
                IF @currentMeasure IS NULL BEGIN -- Start of a period
                    SET @currentMeasure = @measure
                    SET @fromMeasureTime = @measureTime
                END
                SET @toMeasureTime = @measureTime
        END
        ELSE BEGIN
                IF @currentMeasure IS NOT NULL BEGIN -- End of a period
                    INSERT INTO @timeSpans VALUES (@fromMeasureTime, @toMeasureTime)
                    SET @currentMeasure = NULL
                END
        END 
        FETCH NEXT FROM yourCursor INTO @measureTime, @measure
    END

    CLOSE yourCursor
    DEALLOCATE yourCursor

    RETURN
END
GO

select * from dbo.[getTimeSpansBelowMaxTemp]('2015-09-01')

SQL 列出值大于特定值的周期

SQL list periodes where value is more then a spesific value

sql-server

sql-server-2014