fname (PGresult)

    /*
     * call-seq:
     *    res.fname( index ) -> String
     *
     * Returns the name of the column corresponding to _index_.
     */
    static VALUE
    pgresult_fname(VALUE self, VALUE index)
    {
            PGresult *result;
            int i = NUM2INT(index);

            result = get_pgresult(self);
            if (i < 0 || i >= PQnfields(result)) {
                    rb_raise(rb_eArgError,"invalid field number %d", i);
            }
            return rb_tainted_str_new2(PQfname(result, i));
    }