ActiveReports allows reports to contain any number of child reports by using the Subreport control. Child reports, or subreports, are executed each time the parent section (i.e. the section in which the Subreport control is placed) is printed.

Subreports do not render PageHeader/Footer sections, so you can delete them to save on processing time.

This walkthrough illustrates how to set up a bound subreport by setting the Report property of the Subreport control to the child report. This walkthrough also demonstrates how to modify the subreport record source from the data in the parent report to retrieve the correct information.

This walkthrough is split up into the following activities:

Adding two ActiveReports to a Visual Studio project
Connecting the parent report to a data source
Adding controls to display the data
Adding the code needed to save the current record's CategoryID to use in the subreport's SQL query
Adding the code needed to create a new data source for the subreport
Viewing the report

To complete the walkthrough, you must have access to the Northwind database.
A copy is located at C:\Program Files\Data Dynamics\ActiveReports for .NET 3.0\Data\NWIND.MDB.

When you have finished this walkthrough, you will have a report that looks similar to the following.

Adding two ActiveReports to a Visual Studio project

To add two ActiveReports to a Visual Studio project

Open a new project in Visual Studio.
From the Project menu, select Add New Item.
Select ActiveReports 3.0 File and rename the file rptParent.
Click Open.
From the Project menu, select Add New Item.
Select ActiveReports 3.0 File and rename the file rptChild.
Click Open.

Connecting the parent report to a data source

To connect the parent report to a data source

Click the gray report Datasource icon in the Detail section to open the report Datasource dialog.
Click on Build.
Select Microsoft Jet 4.0 OLE DB Provider and click Next.
Click the ellipsis button to browse for the access path to the NorthWind database. Click Open once you have selected the appropriate access path.
Click OK to continue.
In the Query field, type "Select * from categories".
Click OK to return to the report design surface.

Adding controls to display the data

To add controls to the reports

Add the following controls to the Detail section of rptParent, setting the properties as indicated:

Control	DataField	Name	Text	Location
Label		lblProducts	Products	1.15, 0.25
Label		lblCategoryName	Category Name:	0, 0
TextBox	CategoryName	txtCategoryName	CategoryName	1.15, 0
Subreport		subReport1		1.15, 0.5

Add the following controls to the Detail section of rptChild, setting the properties as indicated:

Control DataField Name Text Location

TextBox ProductName txtProductName Product Name 1.15, 0

Label lblProductName Product Name: 0, 0
Set the CanShrink property of the Detail section of rptChild to True

Control	DataField	Name	Text	Location
TextBox	ProductName	txtProductName	Product Name	1.15, 0
Label		lblProductName	Product Name:	0, 0

Adding the code needed to save the current record's categoryID

Note: The Fields collection should never be accessed outside the DataInitialize and FetchData events.

To write the code in Visual Basic

Right-click in any section of the design window of rptParent, and click on View Code to display the code view for the report. At the top left of the code view for rptParent, click the drop-down arrow and select rptParent events. At the top right of the code window, click the drop-down arrow and select FetchData. This creates an event-handling method for rptParent's FetchData event. Add code to the handler to:
- Save the current record's categoryID to use in the subreport's SQL query

To write the code in C#

Click the gray area below rptParent to select the report. Click on the events icon in the Properties window to display available events for the report. Double-click FetchData. This creates an event-handling method for the FetchData event of rptParent. Add code to the handler to:

Save the current record's categoryID to use in the subreport's SQL query

The following example shows what the code for the method looks like.

'Visual Basic
Dim categoryIDString As String
Private Sub rptParent_FetchData(ByVal sender As Object, ByVal eArgs As DataDynamics _
	.ActiveReports.ActiveReport3.FetchEventArgs) Handles MyBase.FetchData
   categoryIDString = Me.Fields("CategoryID").Value
 End Sub

//C#
string categoryIDString;
private void rptParent_FetchData(object sender, DataDynamics.ActiveReports.ActiveReport3.
	FetchEventArgs eArgs)
{
   categoryIDString = Fields["CategoryID"].Value.ToString();
}

Adding the code to create a new data source for the subreport

To write the code in Visual Basic or C#

Double-click the Detail section of rptParent to create an event-handling method for the Detail Format event of rptParent. Add code to the handler to:

Create a new DataDynamics OleDBDataSource
Set the connection string of the new data source
Set the SQL query for the new data source
Set the data source of the subreport equal to the new data source

The following example shows what the code for the method looks like.

'Visual Basic
Private Sub Detail1_Format(ByVal sender As Object, ByVal e As System.EventArgs)_ 
   Handles Detail1.Format
   Dim rpt As New rptChild()
   Dim childDataSource As New DataDynamics.ActiveReports.DataSources.OleDBDataSource()
   childDataSource.ConnectionString = CType(Me.DataSource, DataDynamics.ActiveReports.OleDBDataSource).ConnectionString
   childDataSource.SQL = "Select * from products where categoryID = " + categoryIDString
   rpt.DataSource = childDataSource
   Me.SubReport1.Report = rpt
End Sub

//C#
private void detail_Format(object sender, System.EventArgs eArgs)
{
   rptChild rpt = new rptChild();
   DataDynamics.ActiveReports.DataSources.OleDBDataSource childDataSource = new DataDynamics.
    	ActiveReports.DataSources.OleDBDataSource();
   childDataSource.ConnectionString = ((DataDynamics.ActiveReports.OleDBDataSource)this.DataSource).ConnectionString;
   childDataSource.SQL = "Select * from products where categoryID = " + categoryIDString;
   rpt.DataSource = childDataSource;
   this.subReport1.Report = rpt;
}

Viewing the report

To view the report

Add the ActiveReports viewer control to a Windows Form.
Add the code needed to set the viewer document equal to the report document of rptParent. See Using the ActiveReports Windows Form Viewer for help.

You can quickly view your report at design time by clicking the Preview tab at the bottom of the designer.