title: Filter by NULL in DataTable.Compute()
body: <p>I am trying to execute the following code -</p>
  
  <pre><code>dt.Compute("Count(RetailerId)", "SurveyorDate&lt;&gt;NULL")
  </code></pre>
  
  <p>But it's not giving me the expected result. <strong>SurveyorDate</strong> might by DBNull.Value. I would like to sort them out in my filter expression.</p>
  
  <p>How can i do that?</p>