Update: The issue is not the SteemSQL database, but with my website hosting. there was maintenance on the server. So they closed the ports to the steemsql database, and needed to be reopened. Now it is working again.
更新: 網站又可以用了。原來是我的主机商因為系統維修而把往SteemSQL的端口關了。問題與SteemSQL無關。