title: Datatable.Select sort expression with some sql function
body: <p>I want to use some function in Sort Expression of Datatable.Select.<br>
  I try by this-<br></p>
  
  <pre><code>string strSelect="";
  ///Some code
  string strSort="RIGHT(TESTID,2) DESC,SUBSTRING (TESTID,3,5) DESC, TESTDATE DESC";
  dtOld.Select(strSelect,strSort );
  </code></pre>
  
  <p>but,I think there is something wrong by using sql function(eg.SUBSTRING) in Sort Expression.
  SO, How can I sort my datatable by this sort expression? Is it possible?
  <bR>Thanks.</p>