title: mysql field name from variable
body: <p>is it possible to select field which name is string?</p>
  
  <p><code>SELECT 'fieldname' FROM table</code></p>
  
  <p>i need this for trigger to have dynamic field names
  something like</p>
  
  <pre><code>SET fieldname = NEW.`name`;
  UPDATE table SET fieldname = 1 ; 
  </code></pre>