Linking to Subreport Parameters
If the subreport has parameter fields in it, when the user refreshes the report they are prompted to enter values for the subreport parameters. If you don’t want the user to be prompted to enter a parameter value, you can link a field from the main report to the subreport parameter. This automatically populates the subreport parameter field with a value from the main report without prompting the user.
To link a field from the main report to a subreport parameter, right-click on the subreport in design mode and select Change Subreport Links. This opens the Subreport Links dialog box previously shown in Figure 9-4. In the Available Fields list, double-click the field from the main report that holds the value you want to pass to the subreport parameter. This adds the field to the Fields To Link To list on the right.
When you move a field to the Fields To Link To list, Crystal Reports’ default behavior is to automatically create a matching parameter in the subreport which is passed the value from the main report. If you look in the bottom left hand corner of the dialog box you’ll see that there is a parameter...