HP Intelligent Management Center Standard Software Platform - Manual (Page 641)

Unlinked vs. linked subreports
Unlinked
Unlinked subreports are free-standing; their data is not in any way coordinated
with the data of the primary report.
In unlinked subreports, there is no attempt to match up the records in one
report with records in the other. An unlinked subreport does not have to use
the same data as the primary report; it can use the same data source or a
different data source entirely. In addition, the subreport is not limited to
reporting on a single table. An unlinked subreport can be based on a single
table or on multiple tables. Regardless of the underlying data sources, the
reports are treated as unrelated.
Linked
Linked subreports are just the opposite; their data is coordinated. The
program matches up the records in the subreport with records in the primary
report. If you create a primary report with customer information and a
subreport with order information and link them, the program creates a
subreport for each customer and includes in that subreport all the orders for
that customer.
Database links vs. subreports in one-to-many situations
When two tables in a report have a one-to-many relationship, the program
retrieves the data in different ways depending on:
• Data source.
• Index situation.
• Record selection criteria.
• Whether you are creating a single report based on linked tables or a
primary report that contains a subreport.
Crystal Reports 2008 SP3 User's Guide 641
24 Subreports
What are subreports?