/*      result_metadata()    */
static VALUE stmt_result_metadata(VALUE obj)
{
    struct mysql_stmt* s = DATA_PTR(obj);
    MYSQL_RES *res;
    check_stmt_closed(obj);
    res = mysql_stmt_result_metadata(s->stmt);
    if (res == NULL) {
      if (mysql_stmt_errno(s->stmt) != 0)
        mysql_stmt_raise(s->stmt);
      return Qnil;
    }
    return mysqlres2obj(res);
}