MySQL 5.7 Release Notes
The CREATE FUNCTION
statement is
used to create stored functions and loadable functions:
For information about creating stored functions, see Section 13.1.16, βCREATE PROCEDURE and CREATE FUNCTION Statementsβ.
For information about creating loadable functions, see Section 13.7.3.1, βCREATE FUNCTION Statement for Loadable Functionsβ.