CREATE FUNCTION (external scalar)
The function is written in a programming language and returns a scalar value. The external executable is registered with an application server along with various attributes of the function.
CREATE FUNCTION (external table)
The function is written in a programming language and returns a complete table. The external executable is registered with an application server along with various attributes of the function.
The function is implemented by invoking another function (either built-in, external, or sourced) that is already registered with an application server.