title: In SQL: When 'no results' return from a query show some default results
body: <p>I'm using <code>Postgres</code> to get results from a table.  I want to use SQL to solve a problem.</p>
  
  <p>When my postgresql query returns no results, I would like some default row results to appear.  I am using Jasper-reports, so I don't have a lot of tools to catch the event where there are no results, and then deliver default results.</p>
  
  <p>When the first query DOES show results I do not want the default results to appear.  Currently I'm trying to use a UNION but I want the second query after the <code>Union</code> command to ONLY happen if the first query shows 0 results. </p>
  
  <p>Can this be done in SQL?</p>