A subreport is a report item that displays another report inside the body of a main report. Conceptually, a subreport is similar to a frame in a Web page. It is used to embed a report within a report. Any report can be used as a subreport. The report that the subreport displays is stored on a report server, usually in the same folder as the parent report. You can design the parent report to pass parameters to the subreport. A subreport can be repeated within data regions, using a parameter to filter data in each instance of the subreport.
If you use subreports to display separate groups of data, consider using data regions (tables, matrices, lists, charts, or gauges) instead. Reports with data regions only may perform better than reports that include subreports.
Use data regions when you need to nest groups of data from the same data source within a single data region. Use subreports if you need to nest groups of data from different data sources within a single data region, reuse a subreport in multiple parent reports, or display a standalone report inside of another report. You can create a "briefing book" by placing multiple subreports inside the body of another report.
In Report Designer, if you preview a report that contains subreports, and then change the subreport, the preview may not be updated. To see the changes, click the Refresh button.
Using Parameters in Subreports
To pass parameters from the parent report to the subreport, define a report parameter in the report that you use as the subreport. When you place the subreport in the parent report, you can select the report parameter and a value to pass from the parent report to the report parameter in the subreport.
The parameter that you select from the subreport is a report parameter, not a query parameter. For more information about parameters, see Adding Parameters to Your Report.
You can place a subreport in the main body of the report, or in a data region. If you place a subreport in a data region, the subreport will repeat with each instance of the group or row in the data region. To pass a value from the group or row to the subreport, in the subreport value property, use a field expression for the field containing the value you want to pass to the subreport parameter.
For more information about working with subreports, see How to: Add a Subreport and Parameters (Reporting Services).
Specifying Subreport Names and Locations
To preview a main report that contains a subreport, both reports must be part of the same project. You can design a main report to specify a subreport in a different folder on the same report server. After you make this change, you can no longer see the subreport in the main report in preview. You must view the report on the report server. The syntax you use to specify the subreport depends on whether the report server is in native mode or SharePoint integrated mode. For more information, see How to: Add a Subreport and Parameters (Reporting Services).