There are three types of subreports

a.Unlinked Subreport

ie the subreport doesn't depend on the main report

at all.

b.Linked subreport

A linked subreport is handy when we need to display

related data elements from more than one database table on

a report

c.On-Demand Subreport

If your report has a section that handles a large number of

records, you can put that section into an on-demand

subreport. An on-demand subreport appears as a hyperlink in

the primary report. When you open the primary report, no

data is retrieved for the on-demand subreport until you

drill down on the hyperlink.