Function and insert - Mailing list pgsql-sql

Hi,

I want to do a function that insert a row on a table like :

CREATE FUNCTION ajout_secu(INT4) RETURNS OID    AS 'INSERT INTO test_2 VALUES($1);'    LANGUAGE 'SQL';

PG refuse to accept the type returns oid as the function is not a SELECT.
What can I do ?

thanks for your help,

LP