Convert Date Range to Individual Days

Question

A table called VolumeRequest stores the volume requests by accounts for a date range.

AccountId   StartDate                       EndDate                    


        

Answer 1

I like to use a Dates table such as

CREATE TABLE #Dates(
    DateId INT,
    CalendarDate DATETIME)

filled with dates for whatever range you need. I use this table to join to tables such as VolumeRequest to retrieve the output you requested.

SELECT
    v.AccountId,
    d.CalendarDate,
    SUM(v.DailyVolume)
FROM
    #Dates d INNER JOIN
    VolumeRequest v ON
        d.CalendarDate >= v.StartDate AND
        d.CalendarDate <= v.EndDate
group by
    d.CalendarDate,
    v.AccountId

to fill the #Dates table, I use something like this:

declare @startdate datetime = '6/1/13', @enddate datetime = '7/31/13'

create table #Dates(CalendarDate datetime)

insert into #Dates(CalendarDate)
select
    dateadd(dd, rid-1, @startdate) as calendardate
from (
    select
        ROW_NUMBER() over(order by o.object_id) as rid
    From
        sys.objects o cross apply
        sys.objects o2
) dates
where
    dateadd(dd, rid-1, @startdate) >= @startdate and dateadd(dd, rid-1, @startdate) <= @enddate

Modify to meet your date range needs.

Answer 2

SQLFiddle demo

Using WITH clause and recursion we generate Days table with all days between MIN and MAX dates. Then generate table Accounts with distinct AccountID. Finally JOIN all these tables and group all with SUM.

WITH MINMAX as 
( SELECT MIN(StartDate) as MinDate,
         MAX(EndDate) as MaxDate
  from T
),
DAYS as
( SELECT MinDate as D from MINMAX
  UNION ALL
  SELECT D+1 as D FROM DAYS WHERE D+1<=
    (
      SELECT MaxDate FROM MINMAX  
     )
),
Accounts as 
(
  select distinct AccountID from T
) 

select A.AccountId,Days.D,sum(T.DailyVolume) from Days
CROSS JOIN Accounts A 
JOIN T on A.AccountID=T.AccountID
          AND
          Days.D between T.StartDate and T.EndDate
GROUP BY A.AccountId,Days.D
ORDER BY A.AccountId,Days.D
OPTION (MAXRECURSION 10000)