Function Body

The header section is followed by the function body, consisting of one or more PSQL statements enclosed between the outer keywords BEGIN and END.Multiple BEGIN …​ END blocks of terminated statements may be embedded inside the procedure body.

A stored function can also be located in an external module.In this case, instead of a function body, the CREATE FUNCTION specifies the location of the function in the external module using the EXTERNAL clause.The optional NAME clause specifies the name of the external module, the name of the function inside the module, and — optionally — user-defined information.The required ENGINE clause specifies the name of the UDR engine that handles communication between Firebird and the external module.The optional AS clause accepts a string literal “body”, which can be used by the engine or module for various purposes.