title: How to make all columns allow null before adding a new row?
body: <p>How to make all columns allow null before adding a new row to the datatable  .</p>
  
  <pre><code> dt.Rows.Add(dt.NewRow());
  </code></pre>
  
  <p>This line throws an exception</p>
  
  <blockquote>
    <p>Column XXX does not allow nulls</p>
  </blockquote>
  
  <p>How to fix this problem.</p>