title: Got Exception "Enumeration has either not started or has already finished" when try to get column from Dataset
body: <p>I am trying to filter dataset by using linq.It works fine</p>
  
  <p><strong>Problem :</strong></p>
  
  <p>But i try to get column from this it gives me that exception</p>
  
  <p><strong>Enumeration has either not started or has already finished.</strong></p>
  
  <p>here is my code :</p>
  
  <pre><code>foreach (string columnName in SelectedItems)
                  {
                      var Rate = (from dr in ds.Tables[0].AsEnumerable()
                                  where dr.Field&lt;double&gt;(columnName) &gt; greater &amp;&amp; dr.Field&lt;double&gt;(columnName) &lt; less
                                  select new
                                  {
                                      rate = dr.Field&lt;double&gt;(columnName)
  
                                  }.rate).ToList();
                      if (Rate.Count &gt; 50)
                      {
                          var avg = Rate.CheckRateValue();
  
                      }
  
  
                      i++;
                  }
  </code></pre>
  
  <p>i searched on web and find out the problem that dr.Field(columnName) must be use for single time.So how i can get column from linq query after skiping this code from Select new section.</p>