ftablecol (PGresult)

    /*
     * call-seq:
     *    res.ftablecol( column_number ) -> Fixnum
     *
     * Returns the column number (within its table) of the table from
     * which the column _column_number_ is made up.
     *
     * Raises ArgumentError if _column_number_ is out of range or if
     * the column number from its table is undefined for that column.
     */
    static VALUE
    pgresult_ftablecol(VALUE self, VALUE column_number)
    {
            int n = PQftablecol(get_pgresult(self), NUM2INT(column_number));
            if (n == 0) {
                    rb_raise(rb_eArgError,
                            "Column number from table is undefined for column: %d",
                            NUM2INT(column_number));
            }
            return INT2FIX(n);
    }