Recursive Start of Week Query with SUM - sql-server

Question

I am looking to get the sum of hours worked by week for n weeks in a single result. I came across this little gem that will provide a list of weeks going back n weeks from the current day using a recursive query.
DECLARE #dt DATE = '1900-01-01';
declare #startDate datetime , #endDate datetime
set #startDate = DATEADD(WEEK, DATEDIFF(WEEK, #dt, CURRENT_TIMESTAMP)-10, #dt)
set #endDate = DATEADD(WEEK, DATEDIFF(WEEK, #dt, CURRENT_TIMESTAMP)-1, #dt)
;with T(startday) as
(
select #startDate as startday
union all
select startday + 7
from T
where startday < #endDate
)
select startday as [StartDate], DATEADD(DD, 7, startday) AS [EndDate] from T
If I could use a similar recursive query that would be great. Other wise, I can build a big query with a union of each date range. I have spent more time than I would like to admit on this.
If I try.
DECLARE #monDT DATE = '1900-01-01';
DECLARE #startDate DATETIME , #endDate DATETIME
SET #startDate = DATEADD(WEEK, DATEDIFF(WEEK, #monDT, CURRENT_TIMESTAMP)-10, #monDT)
SET #endDate = DATEADD(WEEK, DATEDIFF(WEEK, #monDT, CURRENT_TIMESTAMP), #monDT)
;WITH T(startDay, endDay, StartDateTime, FinishedDateTime, ActualDurationHours)
AS (
SELECT
#startDate AS startDay,
#endDate AS endDay,
[WorkOrderTrade].[StartDateTime],
[WorkOrderTrade].[FinishedDateTime],
[WorkOrderTrade].[ActualDurationHours]
FROM [WorkOrderTrade]
WHERE [WorkOrderTrade].[TradeContactID] = 783
AND [WorkOrderTrade].[StartDateTime] > #startDate
AND [WorkOrderTrade].[FinishedDateTime] < #endDate
UNION ALL
SELECT
startDay + 7,
endDay,
StartDateTime,
FinishedDateTime,
ActualDurationHours
FROM T
WHERE startDay < #endDate
)
SELECT TOP (100)
startDay,
DATEADD(DD, 7, startday) AS endDay,
SUM(ActualDurationHours)
FROM T
GROUP BY startDay, endDay
It SUMs the total hours across the whole date range as per the recursive portion of the query. I need to come up with a way of filtering the hours in that recursive portion based on the startDay and endDay of each week. Something like the following would be good but you are not allowed to accumulate in the recursive portion.
SELECT
startDay + 7,
StartDateTime,
FinishedDateTime,
(SELECT SUM(ActualDurationHours) FROM [WorkOrderTrade] WHERE [WorkOrderTrade].[TradeContactID] = 783 AND (StartDateTime > startDay AND FinishedDateTime < DATEADD(DD, 7, startDay)))
FROM T
WHERE startDay < #endDate
Is there a way or do I need to build a large UNION query?

Answer 1

Persistence pays off but I had to go out of that box that I was stuck in and use a temporary table and a WHILE loop.
DECLARE #monDT DATE = '1900-01-01';
DECLARE #startDate DATETIME , #endDate DATETIME, #startOfWeek DATETIME
SET #startDate = DATEADD(WEEK, DATEDIFF(WEEK, #monDT, CURRENT_TIMESTAMP)-10, #monDT)
SET #endDate = DATEADD(WEEK, DATEDIFF(WEEK, #monDT, CURRENT_TIMESTAMP)+1, #monDT)
SET #startOfWeek = #startDate
CREATE TABLE #tmpDuration (
StartDate DATETIME,
EndDate DATETIME,
LoggedHours NUMERIC(18,7)
)
WHILE #startOfWeek < #endDate
BEGIN
INSERT INTO #tmpDuration
SELECT
#startOfWeek,
DATEADD(DD, 7, #startOfWeek),
SUM([WorkOrderTrade].[ActualDurationHours])
FROM [WorkOrderTrade]
WHERE [WorkOrderTrade].[TradeContactID] = 783
AND [WorkOrderTrade].[StartDateTime] > #startOfWeek
AND [WorkOrderTrade].[StartDateTime] < DATEADD(DD, 7, #startOfWeek)
SET #startOfWeek = DATEADD(DD, 7, #startOfWeek)
END
SELECT * FROM #tmpDuration
DROP TABLE #tmpDuration