FileMaker Pro 10: The Missing Manual

Chapter 9. Understanding Calculations

When you were learned about tables, fields, and relationships in the previous few chapters, you dabbled in FileMaker’s calculation dialog box. Now it’s time to dive in and learn how calculations can make your database total invoices, analyze trends, calculate dates and times, and so on.

For those tasks, FileMaker provides calculation fields and a whole drawer full of functions that let you examine, compare, combine, and even break apart field values. Calculations aren’t limited to number-crunching tasks. You can use them to find out about the computer your database is running on, track who’s logged into the system, monitor their privileges, and then perform logical tests based on what you find. You’ll start by learning how FileMaker handles calculations, and then you’ll see how some common functions can take your database up to a new level of power.

Understanding Calculations

Way back on Timestamp, you saw how to create a field that’s defined as a calculation. A calculation is a mathematical formula that manipulates the information in your database to give you the answers you need. For example, for a line item on an Invoice, you need to multiply the price of an item by the quantity to get an extended price. To hand that task over to FileMaker, you create a calculation field, and then write a formula that refers to the appropriate fields by name. FileMaker takes the information in the invoice fields, and does the math.

Note

The exercizes in this chapter ...