An unbound main report can serve as a container for unrelated subreports that you want to combine.
The unbound main report contains two subreports.
One subreport summarizes sales by employee.
The other subreport summarizes sales by category.
Example of a main report and subreport that are bound to the same record source
You can use the main report to show detail records, such as every sale in a year, and then use a subreport to show summary information, such as the total sales for each quarter.
The subreport summarizes the year's sales by quarter.
The main report lists the day-to-day sales.
Example of a main report and a subreport that are bound to related record sources
A main report can contain data common to two or more parallel subreports. In this case, the subreport contains data that is related to the data in the main form.
The main report lists the name and city of each fair.
The subreport lists the representatives who will attend each fair.
Subforms in a report
A main report can include subforms as well as subreports, and it can include as many subforms and subreports as you want. Additionally, a main report can contain up to two levels of subforms and subreports. For example, a report can contain a subreport, and that subreport can contain a subform or a subreport. The following table shows the possible combinations of subforms and subreports in a main report.
| Level 1 | Level 2 |
|---|---|
| Subreport 1 | Subreport 2 |
| Subreport 1 | Subform 1 |
| Subform 1 | Subform 2 |
Synchronizing a report and subreport
When you insert a subreport that contains information related to data in the main report, the subreport control must be linked to the main report. The link ensures that the records printed in the subreport correspond correctly to the records printed in the main report.
When you create a subreport by using a wizard or by dragging a report or datasheet from the Database window to another report, Microsoft Access automatically synchronizes the main report and subreport if:
- You have defined relationships for the tables you select, or you have defined relationships for the tables underlying the queries you select.
- The main report is based on a table with a primary key and the subreport is based on a table that contains a field with the same name as that primary key and with the same or a compatible data type. For example, if the primary key of the table underlying the main form is an AutoNumber field and its FieldSize property is set to Long Integer, the corresponding field in the table underlying the subform should be a Number field with its FieldSize property set to Long Integer. If you select a query or queries, the underlying tables in the query or queries must meet the same conditions.
Note The Sales by Category and Sales by Year reports in the Northwind sample database use subreports. To view these reports, open the Northwind database in the Samples subfolder of your Microsoft Office folder, and then open the report in Design view.