iReport-Pass a parameter value from main report's query to subreport's query

In your main report you have to "pass" all the parameters you need to the subreport.

Create required parameters in the main report by right clicking on the parameters section of main report------> add parameter

Copy parameter from master report:

Now go to XML tab:

Let's assume that in your main report you want to pass the CITY parameter to your subreport, you should have something like this code:

    <subreportParameter name="p_registration_no">
      <subreportParameterExpression><![ CDATA[$P{p_registration_no} ]] ></subreportParameterExpression>
    </subreportParameter>

In addition to this, you have to add the same parameter in your subreport (parameters-section).

Note that in the CDATA section you can have more than one parameter and you can pass parameters ($P{p_registration_no}) or fields ($F{donor_registration_no}) as well

Copy parameter & past in sub-report

Use parameter in sub-report