> ## Building a Report That Contains Subreports

> You can build a report that contains multiple reports, called subreports, and you can lay out the subreports in a variety of configurations. BIRT supports many ways of arranging subreports within a single report, such as:

> n | Displaying multiple reports, one after another. For example, you can display the top ten customers, top ten sales representatives, and top ten products.

> n | Displaying multiple reports next to one another. For example, you can display general employee information and employee salary history.

> n | Displaying one report within another. For example, you can display detailed mutual fund performance within general fund information.

> Also, you can combine any of the report configurations that are in the preceding list.

> A subreport is simply a report that appears inside another report. You already know how to create a report. Basically, it takes one additional step to create a report that contains subreports. You must set up the structure of the main report to organize the subreports.

> Each subreport can access a different data source, its own set of tables and fields, and specify its own data selection criteria. Subreports can be linked to one another or be independent of each other. Two reports are linked when the data of one report determines what data appears in another.

> Always create, lay out, and test each subreport before you create the next one, and verify that the subreport displays the correct data. If you skip intermediate testing, it can be difficult, if you have problems, to determine which subreport causes errors.

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