# Formula Reference

A formula is a symbolic statement of the manipulations you want to perform on certain data. JReport provides a number of built-in functions for you to build your formula. Also it provides user-defined formula (UDF) functions that allow you to design your own formula functions according to your requirements. Generally, formulas can be used:

- to calculate information you cannot obtain directly from database data fields,
- to compare data,
- to join text with data,
- to convert data from one form to another,
- to enhance the formatting options with text strings, and
- to do a number of other things to customize your reports.

When the built-in functions cannot satisfy your needs, you can design your own formula functions. JReport provides user-defined formula (UDF) functions to implement it.

This chapter contains the following topics:

- Formula syntax
- Data type
- Built-in functions
- Operators