title: Conversion from type 'DBNull' to type 'String' is not valid vb.net
body: <p>While using the given below code showing one error. The error is: "<code>Conversion from type 'DBNull' to type 'String' is not valid.</code>" Help me to find a proper solution. Thank you.</p>
  
  <p>Code:</p>
  
  <pre><code>cmd2.CommandText = "SELECT [first_name]+' ' +[middle_name]+' ' + [last_name] AS NAME, [staff_id] FROM [staff_profile]"
  sdr2 = cmd2.ExecuteReader
  While sdr2.Read
  drop1l.Items.Add(New ListItem(sdr2("name"), sdr2("staff_id"))) // error popup here
  End While
  sdr2.Close()
  </code></pre>