title: SQL Get "ISO Year" for ISO Week
body: <p>I need to calculate the year a week is assigned to. For example the 29th december of 2003 was assigned to week one of year 2004 (this is only for europe, I think). You can take a look at this with this code:</p>
  
  <pre><code>SELECT DATEPART(isowk, '20141229');
  </code></pre>
  
  <p>But now I need an easy way to get the year this week is assigned to. What I currently do is not that elegant:</p>
  
  <pre><code>DECLARE @week int, @year int, @date char(8)
  
  --set @date = '20150101'
  set @date = '20141229'
  
  
  SET @week = cast(datepart(isowk, @date) as int)
  
  if @week = 1
  begin
        if DATEPART(MONTH, @date) = 12
        begin
              set @year = DATEPART(year, @date) + 1
        end
        else
        begin
              set @year = DATEPART(year, @date)
        end
  end
  
  select @date "DATE", @week "WEEK", @year "YEAR"
  </code></pre>
  
  <p>If anybody knew a more elegant way, that would be nice :-)</p>