title: Jasper Reports: do not render main report when subreports have no data
body: <p><strong>Situation</strong>
  I have a report which consists of a header and four subreports in the detail area.   The subreports get their data by querying a database.   </p>
  
  <p><strong>Requirement</strong>
  If all the subreports have no data, then I would like the main report not to generate - similar to the property "When No Data" set to "No Pages".</p>
  
  <p><strong>Problem</strong>
  Each subreport has the property "Remove Line When Blank" checked so each subreport will only print if it has data.   However in the main report, the query text is "select 1 from dual" so that it will always print.   I want to change this to be dependent on the subreports, so that if all the subreports have no data, it will return nothing and therefore the whole report will not print due to "When No Data" being set to "No Pages".</p>