MySQL Server enables user-defined functions (UDFs) to be created and loaded into the server to extend server capabilities. Server capabilities can be implemented in whole or in part using UDFs. In addition, you can write your own UDFs.
The following sections describe how to install and uninstall UDFs, and how to determine at runtime which UDFs are installed and obtain information about them. For a table listing user-defined functions, see Section 12.2, “User-Defined Function Reference”. For information about writing UDFs, see Adding Functions to MySQL.