Syntax

Element	Purpose	Restrictions	Syntax
language name	The name of the language used to write the external routine	The language name must be the name of a supported external language. (The name of the language must be C.)	Identifier, p.1-966

• The pathname to the executable object code, stored in a shared library
• The name of the language in which the routine is written
• The parameter style of the routine
• The VARIANT or NOT VARIANT option, if you specify one

VARIANT or NOT VARIANT

A variant function does not always return the same value for the same arguments. For example, a function that returns the current date and time or a set of rows from a table is a variant function. In INFORMIX-Universal Server,external functions are variant by default.

A non-variant function always returns the same value when passed the same arguments. To register a non-variant function, add the NOT VARIANT option in the External Routine Reference or in the Routine Modifier clause that is discussed on page 1-1026. If you specify the option in both places, you must use the same option in each.

Example

CREATE FUNCTION equal( a point, b point )
RETURNING BOOLEAN;
EXTERNAL NAME
"/usr/lib/point/lib/libbtype1.so(point1_equal)"
LANGUAGE C
END FUNCTION;

References

For information about how to create and register external routines, see the Extending INFORMIX-Universal Server: User-Defined Routines manual.

Function Name

Syntax

Element	Purpose	Restrictions	Syntax
database	The name of the database where the function resides	The database must exist.	Database Name, p. 1-856
dbservername	The name of the server that is home to database. The @ symbol is a literal character that introduces the database server name.	The database server that is specified in dbservername must match the name of a database server in the sqlhosts file.	Database Name, p. 1-856
owner	The user name of the owner of the function	If you are using an ANSI-compliant database, you must specify an owner if you do not own the function. If you do not specify an owner, the default owner is the current user.	Must conform to the conventions of your operating system.

The actual name of the function is an SQL identifier.

ANSI

The owner name is case sensitive. In an ANSI database, if you type quotation marks around the name, it is stored as you type it. If you do not use quotation marks, the name is stored as uppercase letters. For more information, see the discussion of case sensitivity in ANSI-compliant databases on page 1-1049.

GLS

If you are using a nondefault locale, you can use characters from the code set of your locale in the names of functions. For more information, see the Guide to GLS Functionality.

Routine Overloading

Functions are uniquely identified by their signature. A function's signature includes the following items:

• The routine type (FUNCTION or PROCEDURE)
• The routine name
• The number, data type, and order of the function's parameters

Qualified Function Name

• All arguments passed to the function have built-in data types.
• The instance of the function that is invoked has built-in data types for all of its parameters.
• Any values the function returns have built-in data types.

For information about how to create and use external routines, see the Extending INFORMIX-Universal Server: User-Defined Routines manual. In the Informix Guide to SQL: Tutorial, see Chapter 14 for information about how to create and use SPL routines.