Most business reports require calculations to track sales, finances, inventory, and other critical business activities. Some of this calculated data can be included in the data set. Often, however, a data set does not provide all the data you want to display in your report. In this case, you can create your own calculations by creating a new field called a computed column. Figure 7‑1 shows a BIRT design that uses a computed column, Total, to display the total for each order line item. In this example, the Total values need to be calculated because the data set does not include the total.