CREATE FUNCTION (SQL Form)/
REPLACE FUNCTION (SQL Form)
Relationship Among SQL UDFs, External UDFs, Table UDFs, Methods, and External Procedures.
External UDFs, table UDFs, methods, and external procedures are specific variations of one another and share most properties in common. The generic term used to describe all these is external routine.
SQL UDFs are invoked in the same way as external and table UDFs, but are written in SQL, so they do not have external elements.