tsql – 用于将日期范围转换为每日记录的SQL查询

要求

>我有数据表,可以在日期范围内保存数据.
>允许每条记录与先前的记录重叠(记录具有CreatedOn datetime列).
>新记录可以定义它自己的日期范围,如果它需要可以重叠几个旧记录.
>每个新的重叠记录都会覆盖它重叠的旧记录的设置.

结果集

我需要得到的是每天使用记录重叠的日期范围的数据.它应该返回每天的记录以及该特定日期的相应数据.

要将范围转换为天数,我考虑使用numbers/dates table和用户定义函数(UDF)来获取范围内每一天的数据,但我想知道是否还有其他(如更好*甚至更快)的方式,因为我是使用最新的SQL Server 2008 R2.

存储数据

想象一下,我存储的数据看起来像这样

ID | RangeFrom | RangeTo  | Starts | Ends  | CreatedOn (not providing data)
---|-----------|----------|--------|-------|-----------
1  | 20110101  | 20110331 | 07:00  | 15:00
2  | 20110401  | 20110531 | 08:00  | 16:00
3  | 20110301  | 20110430 | 06:00  | 14:00 <- overrides both partially

结果

如果我想从2011年1月1日到2001年5月31日获取数据,结果表应如下所示(省略明显的行)：

DayDate | Starts | Ends
--------|--------|------
20110101| 07:00  | 15:00  <- defined by record ID = 1
20110102| 07:00  | 15:00  <- defined by record ID = 1
...                          many rows omitted for obvious reasons
20110301| 06:00  | 14:00  <- defined by record ID = 3
20110302| 06:00  | 14:00  <- defined by record ID = 3
...                          many rows omitted for obvious reasons
20110501| 08:00  | 16:00  <- defined by record ID = 2
20110502| 08:00  | 16:00  <- defined by record ID = 2
...                          many rows omitted for obvious reasons
20110531| 08:00  | 16:00  <- defined by record ID = 2

解决方法

Declare @StartDate date
Declare @EndDate date

;With Calendar As
    (
    Select @StartDate As [Date]
    Union All
    Select DateAdd(d,1,[Date])
    From Calendar
    Where [Date] < @EndDate
    )
Select ...
From Calendar
    Left Join MyTable
        On Calendar.[Date] Between MyTable.Start And MyTable.End
Option ( Maxrecursion 0 );

加成

错过了原帖中关于特朗普规则的部分：

Set DateFormat MDY;
Declare @StartDate date = '20110101';
Declare @EndDate date = '20110501';

-- This first CTE is obviously to represent
-- the source table
With SampleData As 
    (
    Select 1 As Id,Cast('20110101' As date) As RangeFrom,Cast('20110331' As date) As RangeTo,Cast('07:00' As time) As Starts,Cast('15:00' As time) As Ends,CURRENT_TIMESTAMP As CreatedOn
    Union All Select 2,'20110401','20110531','08:00','16:00',DateAdd(s,CURRENT_TIMESTAMP )
    Union All Select 3,'20110301','20110430','06:00','14:00',2,CURRENT_TIMESTAMP )
    ),Calendar As
    (
    Select @StartDate As [Date]
    Union All
    Select DateAdd(d,[Date])
    From Calendar
    Where [Date] < @EndDate
    ),RankedData As
    (
    Select C.[Date],S.Id,S.RangeFrom,S.RangeTo,S.Starts,S.Ends,Row_Number() Over( Partition By C.[Date] Order By S.CreatedOn Desc ) As Num
    From Calendar As C
        Join SampleData As S
            On C.[Date] Between S.RangeFrom And S.RangeTo
    )
Select [Date],Id,RangeFrom,RangeTo,Starts,Ends
From RankedData
Where Num = 1   
Option ( Maxrecursion 0 );

简而言之,我对所有样本数据进行排名,这些数据优先于同一日期重叠的较新行.

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