Question

我有一个包含开始日期和报告频率的表格（每1个月，2个月等等。粒度为一个月）

我如何创建一个选择，在实际的一天，将返回最近的未来报告的日期？

Example:  
startDate: 15.01.2015, frequency: 3 months  

if today is 03.01.2016 it should return 15.01.2016  
if today is 16.01.2016 it should return 15.04.2016

不能选择存储上次报告的日期。

编辑：请求的样本数据和预期结果：

Actual date is 05.01.2017

StartDate   Freq        Result
02.01.2016  1month      02.02.2017
06.01.2016  1month      06.01.2017
10.03.2016  3months     10.03.2017
01.01.2015  4months     01.05.2017

Answer 1

好的，让我们玩数学。

计算从某个StartDate每M个月发生的事件的最近发生？

好吧，首先我计算整数除法和模数的remiander，在Month by Frequency之间，以防MONTH（StartDate）= MONTH（ActualDate）

StartDate - ActualDate % Frequency

然后我需要知道已经提取了多少次报告：

Occurrences = StartDate - ActualDate / Frequency

然后添加一个新的事件并乘以你应该添加到StartDate的月数的频率，当DAY（StartDate）＆lt; DAY（ActualDate）。

(Occurrences + 1) * Frequency = Required month

create table #t (StartDate datetime, Freq varchar(10));
insert into #t values
('2016-01-02','1month'),
('2016-01-06','1month'),
('2016-03-10','3months'),
('2015-01-01','4months'),
('2016-01-06','3month');

DECLARE @ActualDate datetime;
SET @ActualDate = '2017-01-05'

SELECT @ActualDate as ActualDate;

;WITH Calc AS
(
    SELECT StartDate, Freq, CAST(LEFT(Freq, 1) AS Int) as intFreq,
           (DATEDIFF(month, StartDate, @ActualDate) / CAST(LEFT(Freq, 1) AS Int)) AS Occurrences,
           (DATEDIFF(month, StartDate, @ActualDate) % CAST(LEFT(Freq, 1) AS Int)) AS restIntDiv,
           DATEPART(day, StartDate) AS StartDay,
           DATEPART(day, @ActualDate) AS ActDay
    FROM #t
)
SELECT StartDate, Freq,
       CASE WHEN restIntDiv = 0 AND ActDay < StartDay
            THEN DATEADD(month, intFreq * (Occurrences), StartDate)
            ELSE DATEADD(month, intFreq * (Occurrences + 1), StartDate)
       END as [NextReport]
FROM Calc;

+---------------------+---------+---------------------+
|      StartDate      |   Freq  | NextReport          |
+---------------------+---------+---------------------+
| 02.01.2016 00:00:00 |  1month | 02.02.2017 00:00:00 |
+---------------------+---------+---------------------+
| 06.01.2016 00:00:00 |  1month | 06.01.2017 00:00:00 |
+---------------------+---------+---------------------+
| 10.03.2016 00:00:00 | 3months | 10.03.2017 00:00:00 |
+---------------------+---------+---------------------+
| 01.01.2015 00:00:00 | 4months | 01.05.2017 00:00:00 |
+---------------------+---------+---------------------+
| 06.01.2016 00:00:00 |  3month | 06.01.2017 00:00:00 |
+---------------------+---------+---------------------+

可在此处查看：http://rextester.com/MBSM51925

Answer 2

我经常使用TVF创建动态日期/时间范围。 Tally表也可以解决这个问题。 UDF比递归CTE更快（特别是对于更大的集合）并提供更多功能。日期范围，日期分数和增量是参数。

Declare @YourTable table (StartDate date,frequency varchar(25))
Insert Into @YourTable values
('2016-01-02','1month'),
('2016-01-06','1month'),
('2016-03-10','3months'),
('2015-01-01','4months')

Select A.*
      ,NextDate=cast(B.RetVal as date)
 From  @YourTable A
 Cross Apply (
                Select Top 1 * From [dbo].[udf-Range-Date](A.StartDate,'2025-01-15','MM',left(A.frequency,1))
                Where RetVal>=cast(GetDate() as date)
             ) B

返回

StartDate   frequency   NextDate
2016-01-02  1month      2017-02-02
2016-01-06  1month      2017-01-06
2016-03-10  3months     2017-03-10
2015-01-01  4months     2017-05-01

UDF如有兴趣

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) 
*/

距离给定日期和频率最近的日期

2 个答案: