This statement is used to register a user-defined function with an application server.
There are three different types of functions that can be created using this statement. Each of these is described separately.
The function is written in a programming language and returns a scalar value. The external executable is registered in the database along with various attributes of the function. See CREATE FUNCTION (External Scalar).
The function is written in a programming language and returns a complete table. The external executable is registered in the database along with various attributes of the function. See CREATE FUNCTION (External Table).
The function is implemented by invoking another function (either built-in, external or sourced) that is already registered in the database. See CREATE FUNCTION (Sourced).