About calculated data
Most BIRT reports require calculations to track sales, finances, inventory, and other critical business activities. You can use Interactive Viewer to create calculations to count items in a warehouse or provide more complex financial data, such as tracking stock portfolio performance over time.
To display calculated data in a report, you create a computed column, such as the Total column in the report shown in
Figure 6‑1. In the example, you need to calculate the Total because the original report does not provide this data.
Figure 6‑1 Report with computed column
In BIRT iHub, Interactive Viewer provides a convenient expression builder wizard to create computed data. You use expression builder to do one of the following:
Enable Interactive Viewer to build an expression.
Select a function to use, then select one or more columns across which Interactive Viewer performs the calculation.
Create a custom expression.
Select a function, then create an expression and validate it, after which Interactive Viewer performs the calculation.
