Sams Teach Yourself MySQL in 21 Days, Second Edition

CREATE [AGGREGATE] FUNCTION function_nameRETURNS {STRING|REAL|INTEGER} SONAME shared_library_name

Description: Creates a new user-defined function (UDF) that may be called as function_name() in the same way as MySQL's built-in functions.

The AGGREGATE option (new in version 3.23) specifies that the function will be an aggregating function (such as COUNT()).

Functions must be written in C or C++. shared_library_name is the name of the compiled .so file, residing in a directory searched by ld.

Limitations: Requires user to have insert privileges for the mysql database. MySQL must have been compiled dynamically, and the operating system must support dynamic loading.

Description in: Day 21

See also: DROP FUNCTION