1. Right-click the Parameters node in the Report Explorer and select Add. This adds a child to the Parameters node.
   
2. Once you add a parameter to the Report Explorer, you can set it up in the Properties window.
3. You can pass the parameter to a field on the report, or access it programmatically.

You can allow users to filter the amount of information exposed in a report through the use of parameters. When you add SQL parameters to a report, ActiveReports displays an Enter Report Parameters dialog where the user can enter the values to pull from the database.

1. Click the gray report DataSource icon on the Detail section band to open the Report Data Source dialog.
   
2. On the OLE DB tab, next to Connection String, click the Build button.
3. In the Data Link Properties window that appears, select Microsoft Jet 4.0 OLE DB Provider and click the Next button.
4. Click the ellipsis (...) button to browse to your database or the sample Northwind database. Click Open once you have selected the appropriate access path.
5. Click OK to close the window and fill in the Connection String field.
6. In the Query field, enter a SQL query like the one below, which contains parameter syntax that ActiveReports uses to generate the following dialog.

   SQL Query. Paste in the Report Data Source window's Query box.	Copy Code
   SELECT * FROM Products INNER JOIN (Orders INNER JOIN [Order Details] ON Orders.OrderID= [Order Details].OrderID) ON Products.ProductID = [Order Details].ProductID WHERE Products.SupplierID = <%SupplierID|Enter Supplier ID|7%> AND OrderDate >= #<%OrderDate|Order date from|11/1/1994|D%># AND Discontinued = <%Discontinued|Is this checked?|true|B%>

7. Click OK to save the data source and return to the report design surface.

The SQL query above causes ActiveReports to display the following dialog to the user. The user can accept these or input other values to select report data.

To understand how this works, see SQL Query Parameters.

The SQL query above contains three parameters: 

• <%SupplierID|Enter Supplier ID|1000%>
• <%OrderDate|Order date|1/1/2001|D%>
• <%Discount|Is this checked?|true|B%>

Each of these parameters follow the syntactical pattern <%FieldName | PromptString | DefaultValue | Type | PromptUser%>

FieldName

The name of the field you wish to request (e.g. SupplierID or OrderDate). This is the only part of the syntax which is required, so you can use <%FieldName%> if you do not wish to use the other values.

Note: Although FieldName is the only required parameter, if you do not specify a DefaultValue for each parameter, the Report Explorer is not populated with bound fields at design time.

PromptString

An optional string value which sets the text that appears in the dialog next to the control (e.g. "Enter Supplier ID: ").

DefaultValue

Sets a default value for the parameter. For example, if you have a date parameter, you can set the DefaultValue for the field to the current date so users can just hit ENTER unless they want to generate a report based on a new date. If you do not supply this value, the Report Explorer is not populated with bound fields at design time.

Type

Indicates the type of data requested. The possible values S for string, D for date, and B for Boolean. If you do not provide a value, string is assumed. 

A string type provides a textbox for input, a date type provides a calendar drop-down control for input, and a Boolean type provides a check box for input.

PromptUser 

Sets whether to prompt the user for a value. The value can be set to True for some parameters and False for others. If you set the report's ShowParameterUI property to False, users are not prompted for any parameters, regardless of the PromptUser value set for any parameter in the report.

Tip: For Strings, if you specify a default value that is enclosed in apostrophes or quotation marks, ActiveReports sends the same marks to SQL. For Boolean parameters, if you specify true/false for the DefaultValue it generates true/false for SQL output. If you specify 0,1, it generates 0 or 1. For date values, enclose the parameter syntax in pound signs, for example, #<%Date%>#

Stored Procedures

You can use stored procedures with parameters in ActiveReports. The SQL query has the stored procedure call and placeholders for the parameters: CustOrderHist <%ID | Enter Customer ID | AFLKI%>.

ActiveReports replaces the parameter with what the user types into the dialog to create a query like this: CustOrderHist 'AFLKI'.

1. Double-click in the gray area below the report to create an event-handling method for the ReportStart event.
2. Add code to the handler to add the parameter at run time.

   Visual Basic.NET code. Paste INSIDE the ReportStart event.	Copy Code
   Dim myParam1 As New Parameter() myParam1.Key = "myParam1" myParam1.Type = Parameter.DataType.String myParam1.PromptUser = True 'set to False if you do not want input from user myParam1.Prompt = "Enter last name:" myParam1.DefaultValue = "This is myParam1 default value" Me.Parameters.Add(myParam1)

3. Back in design view, click in the gray area below the report to select it.
4. Click the events icon in the Properties window to display available events for the report.
5. Double-click FetchData. This creates an event-handling method for the report's FetchData event.
6. Add code to the handler to pass the parameter at run time.

   Visual Basic.NET code. Paste INSIDE the FetchData event.	Copy Code
   'Set textbox text equal to the value of the parameter Me.txtParam1.Text = Me.Parameters("myParam1").Value

1. Double-click in the gray area below the report to create an event-handling method for the ReportStart event.
2. Add code to the handler to add the parameter at run time.

   C# code. Paste INSIDE the ReportStart event.	Copy Code
   Parameter myParam1 = new Parameter(); myParam1.Key = "myParam1"; myParam1.Type = Parameter.DataType.String; myParam1.PromptUser = true; //set to false if you do not want input from user myParam1.Prompt = "Enter last name:"; this.Parameters.Add(myParam1);

3. Back in design view, click in the gray area below the report to select it.
4. Click the events icon in the Properties window to display available events for the report.
5. Double-click FetchData. This creates an event-handling method for the report's FetchData event.
6. Add code to the handler to pass the parameter at run time.

   C# code. Paste INSIDE the FetchData event.	Copy Code
   //Set textbox text equal to the value of the parameter this.txtParam1.Text = this.Parameters["myParam1"].Value;

Add a parameter to the datasource of the subreport as above, either in the sql statement or in code, and ensure that the parameter value exists in the parent report's data. the parameter is passed automatically. The only other consideration is that you need to set the ShowParameterUI property of the subreport to False to prevent the subreport from requesting the parameter value from the user.

You can use parameters with subreports to connect the subreport to the parent report. If you set a parameter for the field that links the parent report to the child subreport, the parent report passes the information to the child through the parameters. Keep the following in mind when working with subreports and parameters:

• Set the subreport's ShowParametersUI property to False.
• Set the subreport's SQL query to use the parameter syntax = <%fieldname%>.

Both report queries must contain the same field (so the main report must have a categoryID field and the subreport also must have a categoryID field.

1. With the chart control highlighted, click the Data Source verb below the Properties Window to open the Chart DataSource dialog. If you do not see the verb, see the Access the Chart Wizard and Data Source topic for more information.
2. On the OLE DB tab, next to Connection String, click the Build button.
3. In the Data Link Properties window that appears, select Microsoft Jet 4.0 OLE DB Provider and click the Next button.
4. Click the ellipsis button to browse to the NorthWind database. Click Open once you have selected the file.
5. Click OK to close the window and fill in the Connection String field.
6. In the Query field, enter a SQL query to select the data that you want.

   SQL Query. Paste in the Query field.	Copy Code
   SELECT * FROM Products WHERE CategoryID = <%CategoryID||1%> ORDER BY ProductName

7. Click OK to save the data source and return to the report design surface.