I’ve got the problem that
select datepart(ww, '20100208')
is returning as result week 7 in SQL Server 2000. But 08.02.2010 should be week 6 according to the ISO 8601 specification! This is causing problems in delivery week calculations.
What should I do to get week number values according to ISO 8601?
You can do this within SQL 2008 very easily as it now supports isoww as the first datepart argument. However, this wasn’t in SQL 2000 (or 2005). There is a function in this article which will do it for you in SQL 2000/2005.
In case the blog goes offline, here is the function. Go to the post to learn more about ISO and non-ISO weeks.
CREATE FUNCTION ISOweek (@DATE datetime) RETURNS int AS BEGIN DECLARE @ISOweek int SET @ISOweek= DATEPART(wk,@DATE)+1 -DATEPART(wk,CAST(DATEPART(yy,@DATE) as CHAR(4))+'0104') --Special cases: Jan 1-3 may belong to the previous year IF (@ISOweek=0) SET @ISOweek=dbo.ISOweek(CAST(DATEPART(yy,@DATE)-1 AS CHAR(4))+'12'+ CAST(24+DATEPART(DAY,@DATE) AS CHAR(2)))+1 --Special case: Dec 29-31 may belong to the next year IF ((DATEPART(mm,@DATE)=12) AND ((DATEPART(dd,@DATE)-DATEPART(dw,@DATE))>= 28)) SET @ISOweek=1 RETURN(@ISOweek) END