Relationship Among Methods, UDFs, and External Procedures
External routines, the generic label used for UDFs, table UDFs, methods, and external procedures, are specific variations of one another and share most properties in common, including being written in a third‑generation programming language such as C or C++.
See “CREATE FUNCTION (External Form)/ REPLACE FUNCTION (External Form)” on page 240, “CREATE FUNCTION (Table Form)” on page 291, and “CREATE PROCEDURE (External Form)/ REPLACE PROCEDURE (External Form)” on page 422 for more information.
When an external routine is invoked, the system passes a handle to the UDT argument instead of the UDT value. Given the handle, an external routine can get, or set, the value of a UDT argument by means of a set of library functions provided by Teradata (see SQL External Routine Programming).
The ANSI SQL standard contrasts external routines with what it refers to as SQL routines, which are routines written in the SQL language. The SQL form of procedures (see “CREATE PROCEDURE (SQL Form)/ REPLACE PROCEDURE (SQL Form)” on page 455 is an example of an SQL routine.