title: Empty DataTextField property of DropDownList
body: <p>I have a <code>DropDownList</code> that is bound to <code>sqlDataSource</code>. Part of the SQL query is: </p>
  
  <pre><code>"Select (firstName +" "+ SecondName +" "+ LastName) AS Name"
  </code></pre>
  
  <p><code>DataTextField</code> property of the <code>DropDownList</code>  is set to <code>Name</code>.</p>
  
  <p>The problem is: if any of (<code>firstName</code>, <code>SecondName</code>, and <code>LastName</code>) equal to <code>NULL</code>, the <code>DataTextField</code> property become empty.</p>
  
  <p>How can I fix this?</p>