title: How to union two data tables and order the result
body: <p>Q: If I have two DataTables like this :</p>
  
  <p><strong>Dt1</strong><code>(emp_num,emp_name,type)</code></p>
  
  <p><strong>Dt2</strong><code>(emp_num,emp_name,type)</code></p>
  
  <p>I wanna to Union them and order the result by <code>emp_name</code>.</p>