使用单列日期分隔记录以共享日期范围

Question

我的付款表中有以下记录。我喜欢做的是根据开始和结束服务日期仅使用一列日期将每条记录分解为单独的记录集。

 DisbursementID ServiceProviderID Original CircuitID   Beginning_Service_Date Ending_Service_Date Amount
 -------------- ----------------- -------- ----------- ---------------------- ------------------- -----------
 53562          673               0        1814        2015-12-01             2015-12-31          531
 53563          673               0        1814        2015-11-01             2015-11-30          531

我的目标是看起来像

 DisbursementID ServiceProviderID Original CircuitID   Date Range  Amount
 -------------- ----------------- -------- ----------- ---------- -------
 53562          673               0        1814        2015-12-01 531
 53562          673               0        1814        2015-12-02 531
 53562          673               0        1814        2015-12-03 531
 53562          673               0        1814        2015-12-04 531
 53562          673               0        1814        2015-12-05 531
 53563          673               0        1814        2015-11-01 531
 53563          673               0        1814        2015-11-02 531
 53563          673               0        1814        2015-11-03 531
 53563          673               0        1814        2015-11-04 531
 53563          673               0        1814        2015-11-05 531

相反，我的结果看起来像

 DisbursementID ServiceProviderID Original CircuitID   Date Range  Amount
 -------------- ----------------- -------- ----------- ---------- -------
 53562          673               0        1814        2015-12-01 531
 53563          673               0        1814        2015-11-01 531
 53563          673               0        1814        2015-11-02 531
 53563          673               0        1814        2015-11-03 531
 53563          673               0        1814        2015-11-04 531
 53563          673               0        1814        2015-11-05 531

以下是我找到但适合我需要的一段代码。它几乎解决了我的问题，但我不知道如何从我的第一条记录中包含范围日期块。我知道它为什么会这样，但不知道如何正确修复它：

 ;With Dates as
 ( 
 Select DisbursementID, ServiceProviderID,Original,CircuitID
 ,Beginning_Service_Date as BeginDate, Ending_Service_Date as EndDate
 ,Amount From Disbursement

 Union All

 Select DisbursementID, ServiceProviderID, Original,CircuitID
 ,DATEADD(day,1,BeginDate) as CalenderDate, EndDate
 ,Amount 
 From Dates
 Where DATEADD(day,1,BeginDate) <= EndDate
 )

 Select DisbursementID, ServiceProviderID,Original,CircuitID
,BeginDate as [Date Range], Amount from Dates
Order By CircuitID
Option (MAXRECURSION 366);

Answer 1

使用递归 cte 是生成日期范围的最糟糕的方法之一。 John Cappelletti 的答案是 much better 用于按需生成日期范围，而不是使用递归 cte。

如果您要在超过 55,000 行中使用它，并且您将多次运行此类操作，那么您最好创建一个 Dates 或 Calendar 表。

只需要 152kb 的内存，你可以在一个表中保存 30 年的日期，你可以像这样使用它：

/* dates table */ 
declare @fromdate date = '20000101';
declare @years    int  = 30;
/* 30 years, 19 used data pages ~152kb in memory, ~264kb on disk */
;with n as (select n from (values(0),(1),(2),(3),(4),(5),(6),(7),(8),(9)) t(n))
select top (datediff(day, @fromdate,dateadd(year,@years,@fromdate)))
    [Date]=convert(date,dateadd(day,row_number() over(order by (select 1))-1,@fromdate))
into dbo.Dates
from n as deka cross join n as hecto cross join n as kilo 
               cross join n as tenK cross join n as hundredK
order by [Date];
create unique clustered index ix_dbo_Dates_date 
  on dbo.Dates([Date]);

并像这样使用Dates 表：

select 
    t.DisbursementID
  , t.ServiceProviderID
  , t.Original
  , t.CircuitID
  , d.[date]
  , t.Amount
from t
  inner join dates d
    --on d.date >= t.Beginning_Service_Date
   --and d.date <= t.Ending_Service_Date
  /* if you want to have the date range work when 
      Beginning_Service_Date and Ending_Service_Date are backwards
      you could use between */
    on d.date between t.Beginning_Service_Date
                  and t.Ending_Service_Date

rextester 演示：http://rextester.com/WNMJW41879

数字和日历表参考：

• Generate a set or sequence without loops - 3 - Aaron Bertrand
• The "Numbers" or "Tally" Table: What it is and how it replaces a loop - Jeff Moden
• Creating a Date Table/Dimension in SQL Server 2008 - David Stein
• Calendar Tables - Why You Need One - David Stein
• Creating a date dimension or calendar table in SQL Server - Aaron Bertrand
• TSQL Function to Determine Holidays in SQL Server - Tim Cullen
• F_TABLE_DATE - Michael Valentine Jones

Answer 2

如果您没有或不能使用计数/日历表，另一种方法是使用临时计数表。

Declare @YourTable table (DisbursementID int, ServiceProviderID int, Original int, CircuitID int, Beginning_Service_Date date, Ending_Service_Date date, Amount int)
Insert Into @YourTable values
 ( 53562,673,0,1814,'2015-12-01','2015-12-31',531)
,( 53563,673,0,1814,'2015-11-01','2015-11-30',531)

;with cte1 as (
                 Select MinDate=min(Beginning_Service_Date)
                       ,MaxDate=max(Ending_Service_Date)
                 From @YourTable )
     ,cte2 as (
                 Select Top (DateDiff(DD,(select MinDate from cte1),(select MaxDate from cte1))+1) 
                        D = DateAdd(DD,-1+Row_Number() Over (Order By (Select null)),(select MinDate from cte1)) 
                  From  master..spt_values A -- ,master..spt_values B  -- If you need more than 6 years
 )
Select A.DisbursementID 
      ,A.ServiceProviderID 
      ,A.Original 
      ,A.CircuitID 
      ,[Date Range] = B.D
      ,A.Amount
 From  @YourTable A
 Join cte2 B on B.D between A.Beginning_Service_Date and A.Ending_Service_Date