FileMaker Pro 11: The Missing Manual

Chapter 15. Advanced Calculations

In the earlier calculation chapters, you learned how calculations can make your databases work harder for you. But the functions you’ve learned so far can’t make your databases work much smarter. For example, what if you want to add a five-percent delinquency charge to invoices over a month old? You could create a special “past due balance” field on a special layout that you use only when you’ve searched for late invoices, but that’s just extra complexity to create, and then maintain, if the late fee rules change later on. On the other hand, if you create a calculation that makes a decision based on current data, you can let the database itself can figure out when to apply late fees, and it works for every invoice, not just the late ones. This chapter shows you how to give your calculations that brainpower by using logical functions and other advanced techniques.

The calculation engine can also be used to give FileMaker features it doesn’t have. You (or someone you hire) can create a plug-in in a programming language like C++. But you don’t have to create a plug-in yourself. Lots of great ones are available from third-parties (Finding Plug-ins). Whether you write a plug-in or buy it, each plug-in adds new functions, like file handling, credit card processing or web services, to FileMaker’s Specify Calculation window.

Note

To create plug-ins, you need FileMaker Pro Advanced. (Chapter 12). Once you’ve installed a plug-in, though, it can be used in any ...