title: Add a column to an IEnumerable in c#
body: <p>I don't think I can actually add a field (column) to an existing IEnumerable.  But what I want is a new IEnumerable that is derived from an existing IEnumerable with a calculated field.  The pseudocode in WebMatrix using Web Pages looks like:</p>
  
  <pre><code>var db = Database.Open("LOS");
  var ie = db.Query(sqlAssignments);
  
  // make a new ie2 that has an extra field
  // ??? ie2 &lt;=== ie with new field c = ie.a + ie.b
  
  var grid = new WebGrid( ie2, extra parameters );
  </code></pre>
  
  <p>I know how to do this looping through all the rows in ie.  But I'm hoping there's something more elegant.</p>