title: How to Express a 2-hour Interval from Now Backwards in SQL in DBVisualizer
body: <p>in Vertica DB, I need to build a query selecting all rows with the timestamp within the past period of two hours from now. This doesn't work, however:</p>
  <pre><code>select * from device_health_1
  where timeframe &gt;= current_timestamp - interval 2 hour  
  </code></pre>
  <p>NOW() doesn't seem to work, either.<br />
  Would appreciate suggestions.
  Thanks!</p>