title: Filling in missing dates in datatable using a linq group by date query
body: <p>I am trying to fill missing date in data table for report.
  for example:</p>
  
  <p>data table collection :</p>
  
  <pre><code>2010-01-01 : 5
  2010-01-02 : 4
  2010-01-03 : 2
  2010-01-05 : 6
  </code></pre>
  
  <p>but I want result like this:</p>
  
  <pre><code>2010-01-01 : 5
  2010-01-02 : 4
  2010-01-03 : 2
  2010-01-04 : 0
  2010-01-05 : 6
  
  var total = from row in dt2.AsEnumerable() 
              where row.Field&lt;UInt32&gt;("Super Category") == j 
              group row by row.Field&lt;string&gt;("Activation Date") into sales 
              orderby sales.Key 
              select new 
                     { 
                         Name = sales.Key, 
                         CountOfClients = sales.Count() 
                     };
  </code></pre>
  
  <p>How can I do that?</p>