Usually when you create a report, the data
needed already exists in the database table fields. For example, to prepare an
order list you would place the appropriate fields on the report.
Sometimes, however, you need data that
does not exist in any of the data fields. In such cases, you need to create a
formula. For example, to calculate the number of days it takes to process each
order, you need a formula that determines the number of days between the order
date and the ship date.
Crystal Reports makes it easy for you to create such a
formula.