title: mysql : create virtual column et set defaut value
body: <p>I have this mysql query :</p>
  
  <pre><code>Select name from my_table
  </code></pre>
  
  <p>This query return me this result :</p>
  
  <pre><code> NAME
  -------
   name1
   name2
   name3
  </code></pre>
  
  <p>How can I create a virtual column and set a defaut value in this column ?
  I want this result :</p>
  
  <pre><code> NAME   | Virtual Column
  ------------------------  
   name1  |    defaut_value
   name2  |    defaut_value
   name3  |    defaut_value
  </code></pre>