Question

SELECT 
    AVG(value) AS total, 
    DATEADD(minute, DATEDIFF(minute, 0, reading_time), 0) AS created
FROM 
     ...  
GROUP BY
     DATEADD(minute, DATEDIFF(minute, 0, reading_time), 0)

此查询按分钟汇总数据。

如何以15分钟的间隔汇总相同的数据？

Answer 1

在派生表中执行日期/时间操作。然后GROUP BY结果：

select avg(value) as total, reading_date, reading_15_mins
from
(
    SELECT value,
           CAST(reading_time as DATE) as reading_date,
           DATEPART(MINUTE, reading_time) / 15 as reading_15_mins
    FROM tablename 
) dt
GROUP BY reading_date, reading_15_mins

受到sagi的回答的启发。谢谢！

Answer 2

我肯定会为此创建一个日期表。这样做的好处是，即使没有数据，您也会返回每个时间段。

测试日期表

IF OBJECT_ID('tempdb..#DateTable') IS NOT NULL DROP TABLE #DateTable
GO
CREATE TABLE #DateTable (QuarterHour datetime)
INSERT INTO #DateTable (QuarterHour)
VALUES
 ('2016-06-27 12:00:00.000')
,('2016-06-27 12:15:00.000')
,('2016-06-27 12:30:00.000')
,('2016-06-27 12:45:00.000')
,('2016-06-27 13:00:00.000')
,('2016-06-27 13:15:00.000')

样本数据

IF OBJECT_ID('tempdb..#SampleData') IS NOT NULL DROP TABLE #SampleData
GO
CREATE TABLE #SampleData (SampleID int identity(1,1), Reading_Time datetime, Value int)
INSERT INTO #SampleData (Reading_Time, Value)
VALUES
 ('2016-06-27 12:01:00.000',7)
,('2016-06-27 12:25:00.000',12)
,('2016-06-27 12:59:00.000',5)
,('2016-06-27 12:33:00.000',6)
,('2016-06-27 12:27:00.000',2)
,('2016-06-27 12:08:00.000',9)
,('2016-06-27 13:16:00.000',7)
,('2016-06-27 12:47:00.000',50)

查询

SELECT
dt.QuarterHour
,AVG(sd.Value) Value
FROM #DateTable dt
LEFT JOIN #SampleData sd
ON dt.QuarterHour = dateadd(minute, datediff(minute,0,sd.Reading_Time) / 15 * 15, 0)
GROUP BY dt.QuarterHour

结果集

QuarterHour                 Value
2016-06-27 12:00:00.000     8
2016-06-27 12:15:00.000     7
2016-06-27 12:30:00.000     6
2016-06-27 12:45:00.000     27
2016-06-27 13:00:00.000     NULL
2016-06-27 13:15:00.000     7

日期表有一些明显的优点，其中一个是性能时间。如果您有兴趣，可以在下面阅读更多内容

https://dba.stackexchange.com/questions/74957/best-approach-for-populating-date-dimension-table

https://www.mssqltips.com/sqlservertip/4054/creating-a-date-dimension-or-calendar-table-in-sql-server/

Answer 3

我使用UDF创建动态日期范围（见下文）

Declare @Date1 DateTime = '2016-06-27'
Declare @Date2 DateTime = '2016-06-28'
Declare @Incr  int      = 15

Select DateR1
      ,DateR2
      ,Total = avg(value)
 From YourTable A
 Join (Select DateR1=RetVal,DateR2=DateAdd(MI,@Incr,RetVal) from [dbo].[udf-Create-Range-Date](@Date1,@Date2,'MI',@Incr) Where RetVal<@Date2) B
   on Reading_Time between DateR1 and DateR2 and ReadingTime < DateR2

UDF ......还有许多其他技术可用。

CREATE FUNCTION [dbo].[udf-Create-Range-Date] (@DateFrom datetime,@DateTo datetime,@DatePart varchar(10),@Incr int)

Returns 
@ReturnVal Table (RetVal datetime)

As
Begin
    With DateTable As (
        Select DateFrom = @DateFrom
        Union All
        Select Case @DatePart
               When 'YY' then DateAdd(YY, @Incr, df.dateFrom)
               When 'QQ' then DateAdd(QQ, @Incr, df.dateFrom)
               When 'MM' then DateAdd(MM, @Incr, df.dateFrom)
               When 'WK' then DateAdd(WK, @Incr, df.dateFrom)
               When 'DD' then DateAdd(DD, @Incr, df.dateFrom)
               When 'HH' then DateAdd(HH, @Incr, df.dateFrom)
               When 'MI' then DateAdd(MI, @Incr, df.dateFrom)
               When 'SS' then DateAdd(SS, @Incr, df.dateFrom)
               End
        From DateTable DF
        Where DF.DateFrom < @DateTo
    )
    Insert into @ReturnVal(RetVal) Select DateFrom From DateTable option (maxrecursion 32767)
    Return
End

-- Syntax Select * from [dbo].[udf-Create-Range-Date]('2016-10-01','2020-10-01','YY',1) 
-- Syntax Select * from [dbo].[udf-Create-Range-Date]('2016-10-01','2020-10-01','DD',1) 
-- Syntax Select * from [dbo].[udf-Create-Range-Date]('2016-10-01','2016-10-31','MI',15) 
-- Syntax Select * from [dbo].[udf-Create-Range-Date]('2016-10-01','2016-10-02','SS',1)

SQL Server聚合15分钟

3 个答案: