使用SQL Server，我想在給定的時間間隔

Question

的數據是如下平均彙總數據：

Time_Stamp(Datetime)  Value (real) 
---------    ----- 
12:01      1.3 
12:02      1.7 
12:04      2.0 
12:08      1.8 
12:11      1.1 
12:12      2.0 

我希望能夠通過定期平均價值 來概括這個數據。所以，如果我選擇了5分鐘，例如間隔輸出將

Timestamp Value 
--------- ------ 
12:00  1.66 
12:05  1.8 
12:10  1.55 

問候

Answer 1

我經常使用TVF來創建動態的日期/時間範圍。一個理貨表也可以做到這一點。 UDF比遞歸更快，並提供更多功能，即定義日期範圍，DatePart和增量。

Declare @YourTable table (Timestamp time,Value money) 
Insert Into @YourTable values 
('12:01',1.3), 
('12:02',1.7), 
('12:04',2.0), 
('12:08',1.8), 
('12:11',1.1), 
('12:12',2.0) 

Select TimeStamp=R1 
     ,Average=Avg(Value) 
From (Select RetSeq,R1=cast(RetVal as Time),R2=cast(DateAdd(MI,5,RetVal) as Time) from [dbo].[udf-Range-Date]('1900-01-01','1900-01-02','MI',5)) A 
Join @YourTable B on B.TimeStamp>=A.R1 and B.TimeStamp<A.R2 
Group By R1 
Order By R1 

返回

TimeStamp   Average 
12:00:00.0000000 1.6666 
12:05:00.0000000 1.80 
12:10:00.0000000 1.55 

的UDF如果需要

CREATE FUNCTION [dbo].[udf-Range-Date] (@R1 datetime,@R2 datetime,@Part varchar(10),@Incr int) 
Returns Table 
Return (
    with cte0(M) As (Select 1+Case @Part When 'YY' then DateDiff(YY,@R1,@R2)/@Incr When 'QQ' then DateDiff(QQ,@R1,@R2)/@Incr When 'MM' then DateDiff(MM,@R1,@R2)/@Incr When 'WK' then DateDiff(WK,@R1,@R2)/@Incr When 'DD' then DateDiff(DD,@R1,@R2)/@Incr When 'HH' then DateDiff(HH,@R1,@R2)/@Incr When 'MI' then DateDiff(MI,@R1,@R2)/@Incr When 'SS' then DateDiff(SS,@R1,@R2)/@Incr End), 
     cte1(N) As (Select 1 From (Values(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) N(N)), 
     cte2(N) As (Select Top (Select M from cte0) Row_Number() over (Order By (Select NULL)) From cte1 a, cte1 b, cte1 c, cte1 d, cte1 e, cte1 f, cte1 g, cte1 h), 
     cte3(N,D) As (Select 0,@R1 Union All Select N,Case @Part When 'YY' then DateAdd(YY, N*@Incr, @R1) When 'QQ' then DateAdd(QQ, N*@Incr, @R1) When 'MM' then DateAdd(MM, N*@Incr, @R1) When 'WK' then DateAdd(WK, N*@Incr, @R1) When 'DD' then DateAdd(DD, N*@Incr, @R1) When 'HH' then DateAdd(HH, N*@Incr, @R1) When 'MI' then DateAdd(MI, N*@Incr, @R1) When 'SS' then DateAdd(SS, N*@Incr, @R1) End From cte2) 

    Select RetSeq = N+1 
      ,RetVal = D 
    From cte3,cte0 
    Where D<=@R2 
) 
/* 
Max 100 million observations -- Date Parts YY QQ MM WK DD HH MI SS 
Syntax: 
Select * from [dbo].[udf-Range-Date]('2016-10-01','2020-10-01','YY',1) 
Select * from [dbo].[udf-Range-Date]('2016-01-01','2017-01-01','MM',1) 

Answer 2

SELECT Timestamp, 
     AVG(VALUE) AS Value 
    FROM 
    (
     SELECT CASE WHEN Timestamp BETWEEN 12:00 AND 12:05 THEN 12:00 
        WHEN Timestamp BETWEEN 12:05 AND 12:10 THEN 12:05 
        WHEN Timestamp BETWEEN 12:10 AND 12:15 THEN 12:10 
       END AS Timestamp, 
       VALUE 
      FROM data 
    ) 
GROUP BY Timestamp; 

Answer 3

一種方法是創建一個time table。您可以將所需的任何字段添加到此表格中，從而爲您提供分組。

此示例使用recursion返回一個簡單的時間表，用於說明目的。在你的數據庫中，我建議創建一個合適的表。

-- Sample time table. 
WITH DimTime AS 
    (
     -- Returns one record for each minute of the day. 
      SELECT 
       CAST('00:00:00' AS TIME(0)) AS TimeKey, 
       0       AS [Hour], 
       1       AS AM 

     UNION ALL 

      SELECT 
       c.NextMinute             AS TimeKey, 
       DATEPART(HOUR, c.NextMinute)         AS [Hour], 
       CASE WHEN DATEPART(HOUR, c.NextMinute) < 12 THEN 1 ELSE 0 END AS AM 

      FROM 
       DimTime AS t 
        CROSS APPLY 
         (
          VALUES 
           (DATEADD(MINUTE, 1, TimeKey)) 
         ) AS c(NextMinute) 
      WHERE 
       t.TimeKey < CAST('23:59:00' AS TIME(0)) 
    ) 
SELECT 
    * 
FROM 
    DimTime 
OPTION 
    (MAXRECURSION 1440) 
; 

返回

TimeKey  Hour AM 
00:00:00 0  1 
00:01:00 0  1 
... 
11:59:00 11  1 
12:00:00 12  0 
... 
23:59:00 23  0 

將一列呼籲沿FiveMinuteInterval東西線將簡化您的最終查詢。