title: Android sqlite - select records where field is null or empty
body: <p>My application has an sqlite DB, where some of the fields are null or empty (meaning that I never inserted anything into that field).</p>
  
  <p>I wish to select all the records for which the field is null or empty.</p>
  
  <p>This is what I have tried:</p>
  
  <pre><code>cursor = db.query(DBHelper.TABLE_NAME, COLUMNS, "folder_name = ? ", new String[] {"null"}, null, null, DBHelper.TIMESTAMP_COL + " DESC");
  </code></pre>
  
  <p>But that didn't work, and I didn't get any records. What do I need to do to make this work?</p>