title: Group by Week of year (Week number) in Linq to SQL
body: <p>In regular SQL i could do something like</p>
  
  <pre><code>SELECT * From T GROUP BY DATEPART(wk, T.Date)
  </code></pre>
  
  <p>How can i do that in Linq to SQL ?</p>
  
  <p>The following don't work </p>
  
  <pre><code>From F In DB.T Group R By DatePart(DateInterval.WeekOfYear, F.Date)
  </code></pre>
  
  <p>Also don't work:</p>
  
  <pre><code>From F In DB.T Group R By (F.Date.DayOfYear / 7)
  </code></pre>