title: Type of conditional expression cannot be determined because there is no implicit conversion between 'string' and 'System.DBNull'
body: <pre><code>param7[1].Value = tbLastName.Text.Length &gt; 0 ? tbLastName.Text : DBNull.Value;
  </code></pre>
  
  <p>Why is this impossible, and any suggestion what else to try? If/else for 20 parameters is just not way.</p>