A Sub-report is a report within another report. Following are the steps to create a sub-report in report designer:
STEP 1: Open pentaho report designer. Add a data source.
STEP 2: ADD another data source in the same report. Give QueryName as SubReport.
STEP 3: Drag the sub Report icon to page.
STEP 4: Set the sub report properties as follows:
FILE PATH: This is the path of the sub report.
QUERY: Select the query name for the subreport. E.g. subreport.
STEP 5: Now double click on the sub report field and save it with name subreport2. Another window will be open.
STEP 6: Drag the fields to page area.
STEP 7: Run the main project.