SET ANSI_NULLS OFF
GO
SET QUOTED_IDENTIFIER ON
GO

CREATE FUNCTION WEEKPERIODE  (@FLTIME FLOAT, @DATUM DATETIME)
RETURNS INT
AS
BEGIN
	DECLARE @WEEKPERIODE INT
	DECLARE @FLTDATE DATETIME
	DECLARE @MAXDATE DATETIME
	DECLARE @MINDATE DATETIME
	DECLARE @DAYOW INT

	SET @FLTDATE = CAST(CONVERT(varchar, DATEADD(s, @FLTIME, '1980'), 101) AS DATETIME)
		
	SET @DATUM = CAST(CONVERT(varchar, DATEADD(w,-1, @DATUM), 101) AS DATETIME)
	SET @DAYOW = DATEPART(dw,@DATUM)
	SET @MAXDATE = CAST(CONVERT(varchar, DATEADD(d,-@DAYOW, @DATUM), 101) AS DATETIME)
	SET @MINDATE = CAST(CONVERT(varchar, DATEADD(d,-27, @MAXDATE), 101) AS DATETIME)
	
	IF (@FLTDATE >= @MINDATE) AND (@FLTDATE <= @MAXDATE) SET @WEEKPERIODE = 1
	ELSE SET @WEEKPERIODE = 0
	
	RETURN(@WEEKPERIODE)
END

GO