Thank you Jeff, great!
Cheers,
Julian
(https://www.red-gate.com/simple-talk/sql/t-sql-programming/sql-server-apply-basics/)
DECLARE @IDHUIS VARCHAR(4)
DECLARE @IDAFD VARCHAR(4)
DECLARE @JAAR INT
DECLARE @WEEKBEGIN INT
DECLARE @WEEKEND INT
SET @IDHUIS = 'XX'
SET @IDAFD = 'A03'
SET @JAAR = 2017
SET @WEEKBEGIN = 1
SET @WEEKEND = 52
SELECT dt.IsoYear,
dt.IsoWkNr as IsoWeek,
SUM(ISNULL(ca.UrenMeerzorg,0)/7) as HrsMeerzorg
FROM dbo.dimTime dt
OUTER APPLY
(
SELECT TOP 1 M.UrenMeerzorg
FROM dbo.Meerzorg M JOIN HuisAfdeling H ON
M.IDHuis = H.IDHuis AND
M.IDAfd = H.IDAfd
WHERE M.Active = 1
AND (M.IDHuis = @IDHUIS or @IDHUIS IS NULL)
AND (H.IDAfd = @IDAFD or @IDAFD IS NULL)
AND H.MeeTellen <> 'NEE'
AND M.[DatumData] <= dt.[Date]
ORDER BY M.[DatumData] DESC
) ca
WHERE IsoYear = @JAAR
AND (IsoWkNr >= @WEEKBEGIN OR @WEEKBEGIN IS NULL)
AND (IsoWkNr <= @WEEKEND OR @WEEKEND IS NULL)
GROUP BY IsoYear, IsoWkNr
ORDER BY IsoWkNr