Parameters can be used to create expressions for calculated fields. To use parameters to perform various calculations in the report, perform the steps below:

1. Run FlexReportDesigner.exe application.
2. Create a new report. Bind it to Products table. The report opens in the Design mode.
3. Click the Data tab.
4. Right-click Data Sources and select Add Data Source. The Data Sources dialog box appears.
5. Add another Data source and bind it to Products table. This data source is added for the parameter. Name this data source as 'dsProducts'.
6. Add a parameter 'Parameter0' by right-clicking Parameters and then selecting Add Parameter. 
7. From the Properties window, click the ellipsis button next to AllowedValuesDefinition. The AllowedValuesDefinition Editor dialog box appears.
8. Select the From Data Source radio button and then select Data Source - dsProducts, Label - ProductName, and Value - ProductName. Click OK.
9. Add another parameter 'Discount'.
10. Edit the 'Main' data source. Write following Sql statement:
    Select * from Products where ProductName=Parameter0
11. Add a Calculated field from the Fields group in the Insert tab. The VBScript Editor opens.
12. Specify the following expression in the editor:
    UnitPrice*Discount
13. Drop the Calculated field in the Detail section. Also add a Text field to display 'Discounted Price' in the PageHeader section.

    

14. Preview the report. Select the product name from Parameter0 and enter the discount value in Discount parameter. The discounted price is calculated on clicking Apply Parameters.