The CREATE FUNCTION statement registers user-defined functions
in the database. The CREATE PROCEDURE statement registers user-defined
procedures in the database. These functions store information about
the UDR in the sysprocedures system catalog table.
Registration for a C UDR requires the following special clauses
of the CREATE FUNCTION and CREATE PROCEDURE statements to help the
database server identify the routine:
The required EXTERNAL NAME clause specifies the path to the shared-object
file that contains the compiled C code for the UDR.
The required LANGUAGE clause specifies the language in which the
body of the UDR is written.
The optional WITH clause specifies the routine modifiers for the
UDR.
For example, the following figure shows a CREATE FUNCTION statement
that registers a user-defined function named abs_eq() whose
corresponding C function is in a shared-object file named abs.so. Figure 1: Registering a C UDR
