title: Add Column to current DataTable with linq
body: <p>Can we add a new Column which is calculated Column in a existing DataTable</p>
  
  <pre><code>dt1.Rows.Add(new string[] { "1", "a", "a1" });
  
  dt1 = (from r in dt1.AsEnumerable()
  select new {
  col3 = r.Field&lt;string&gt;("col1") + r.Field&lt;string&gt;("col2") 
  });
  </code></pre>
  
  <p>resulting DataTable should contain the new Column</p>