A computed column is a column whose content is computed from values in other columns in the table. Computed columns are not available in all DBMSs.
Simple computed expressions can be entered directly in the Computed expression field on the Detail tab of the column property sheet. For more complex expressions, click the Edit tool to the right of the field to access the SQL Editor (see Writing SQL Code in the PowerDesigner SQL Editor).
In the following example a column must be filled with the total sales of widgets computed by multiplying the number of widgets by the widget price: