title: T SQL Datepart and Count - Show also weeks with zero count
body: <p>I have following SQL statement:</p>
  
  <pre><code>declare @dateFrom datetime = '2015-01-01'; 
  declare @dateTo datetime = '2015-12-31'; 
  
  select 
      DATEPART(WEEK, OrderDate) Week, Count(*) Number
  from 
      table 
  where 
      OrderDate between @dateFrom and @dateTo 
  group by 
      DATEPART(WEEK, OrderDate) 
  order by 
      Week
  </code></pre>
  
  <p>It returns the number of orders per week, but if there were no orders at all this respective week is omitted.</p>
  
  <p>How can I change the statement so it will also include weeks with 0 orders? </p>