SQL：从一组日期范围创建新的日期范围组

Question

我正在尝试为我的问题找到合适的标题，到目前为止已经尝试了 30 分钟...:) 到目前为止，我有以下示例

DateFrom    DateTo   Amount 
2015/01/01 2015/08/31 1$ 
2015/01/01 2015/12/31 3$
2015/08/01 2015/12/31 7$

第一行我们得到 0.125 美元/月（1 美元/8 个月）
对于第二行，我们得到 0.25 美元/月（3 美元/12 个月）
对于第 3 行，我们得到 1.4 美元/月（7 美元/5 个月）

考虑到上述情况，我们想创建一组新的日期范围以获得金额总和。类似于下面的结果：

DateFrom    DateTo          Amount
2015/01/01 2015/07/31    (0.125$+0.25$)*7 =2.625$
2015/08/01 2015/08/31    (1.4$+0.125$+0.25$)*1  =1.775$
2015/09/01 2015/12/31    (1.4$+0.25$)*4   =6.6$

以上加起来和原来的数据一样是11$。我们想要的结果实际上是每组唯一日期范围的金额总和。

这可以用 SQL 实现吗？

Answer 1

解决方案不是很优雅，可能有一些不必要的部分，但它产生了正确的结果：

SELECT * INTO tbl_Periods
FROM ( VALUES
('2015/01/01','2015/08/31',1),
('2015/01/01','2015/12/31',3),
('2015/08/01','2015/12/31',7)) as x(DateFrom,DateTo,Amount);
GO
;WITH 
  Pass0 as (select 1 as C union all select 1),
  Pass1 as (select 1 as C from Pass0 as A, Pass0 as B),
  Pass2 as (select 1 as C from Pass1 as A, Pass1 as B),
  Pass3 as (select 1 as C from Pass2 as A, Pass2 as B)
, CTE1 as (
    SELECT *,  Amount / DateDiff(MONTH, DateFrom, DATEADD(day, 1 ,DateTo)) as MRate
    FROM tbl_Periods
)
, CTEM as (SELECT MIN(DateFrom) as MinDate,  DATEADD(day, 1, MAX(DateTo) ) as MaxDate
    ,  DateDiff(MONTH, MIN(DateFrom), DATEADD(day, 1, MAX(DateTo) )) as NPeriods FROM tbl_Periods)
, CTEP as (
    SELECT TOP ((SELECT NPeriods FROM CTEM)) ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) as RNumber 
    FROM Pass3 as p
    )
, PeriodList as (
    SELECT DateAdd(month, RNumber-1,MinDate) as PeriodStarts, DateAdd(month, RNumber,DATEADD(day,-1,MinDate)) as PeriodEnds
    FROM CTEM as m CROSS JOIN CTEP as p)
, MPerriods as (
    SELECT * 
    FROM CTE1 as c 
    INNER JOIN PeriodList as l
    ON l.PeriodStarts between c.DateFrom and c.DateTo)
, CPeriods as (
    SELECT PeriodStarts, PeriodEnds, SUM(MRate) as MRate
        , RNK  = RANK() OVER(ORDER BY PeriodStarts)
            - RANK() OVER(PARTITION BY SUM(MRate) ORDER BY PeriodStarts)
    FROM MPerriods
    GROUP BY PeriodStarts, PeriodEnds
) 
SELECT MIN(PeriodStarts) as PeriodStarts, MAX(PeriodEnds) as PeriodEnds, COUNT(*) * MRate
FROM CPeriods
GROUP BY MRate, RNK
ORDER BY 1;
GO

SQL：从一组日期范围创建新的日期范围组

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