title: PDI: how to combien IF and ISBLANK on formula step?
body: <p>In my DB table, I have a column called <code>type</code> and its possible values are "A", "B" or Null.
  If It's Null, I want to replace it to "C", otherwise no change.
  So here's what I did on formula step:</p>
  
  <pre><code>IF(ISBLANK([type]);"C")
  </code></pre>
  
  <p>However I can an error message saying:  Please specify a Boolean type for field [type] as a result of formula [IF(ISBLANK([type]);"C")].</p>
  
  <p>Where's the prob?</p>