title: How to check for NULL or empty value in fql (fast search)?
body: <p>I want to check for null or empty field in fql query , I want to add condition to retrieve result when is column not equal empty or null,  I've tried these ways : </p>
  
  <pre><code>     &lt;Context&gt;
       &lt;QueryText language='en-US' type='FQL'&gt;and(string("Text"),not(Column_Name:equals(" ")))
       &lt;/QueryText&gt;
    &lt;/Context&gt;
  
  
       &lt;Context&gt;
       &lt;QueryText language='en-US' type='FQL'&gt;and(string("Text"),filter(Column_Name:not(" ")))
       &lt;/QueryText&gt;
    &lt;/Context&gt;
  </code></pre>
  
  <p>I also tried "^$" regular expression instead of empty string , but doesn't work .</p>
  
  <p>any ideas ?? </p>