On Sep 17, 2020, at 2:40 AM, 纽约城门口的小木匠 ■ <470138890 at qq.com> wrote: > > I want to limit the number of users online to 1 at the same time. Is it OK to operate the database only?\ Yes, you can enforce Simultaneous-Use with only an SQL database. It's fine. Alan DeKok.