sudo service mysql stop
sudo service mysql start

Job for mysql.service failed.
See "systemctl status mysql.service" and "journalctl -xeu mysql.service" for details.
root@ubuntu-s-1vcpu-512mb-10gb-nyc1-01:/etc/nginx/site# systemctl status mysql.service
× mysql.service - MySQL Community Server
     Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
     Active: failed (Result: oom-kill) since Fri 2022-10-07 22:05:47 UTC; 3s ago
    Process: 4718 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
    Process: 4726 ExecStart=/usr/sbin/mysqld (code=killed, signal=KILL)
   Main PID: 4726 (code=killed, signal=KILL)
     Status: "Server startup in progress"
        CPU: 738ms

Oct 07 22:05:47 ubuntu-s-1vcpu-512mb-10gb-nyc1-01 systemd[1]: mysql.service: A process of this unit has been killed by the OOM killer.
Oct 07 22:05:47 ubuntu-s-1vcpu-512mb-10gb-nyc1-01 systemd[1]: mysql.service: Main process exited, code=killed, status=9/KILL
Oct 07 22:05:47 ubuntu-s-1vcpu-512mb-10gb-nyc1-01 systemd[1]: mysql.service: Failed with result 'oom-kill'.
Oct 07 22:05:47 ubuntu-s-1vcpu-512mb-10gb-nyc1-01 systemd[1]: Failed to start MySQL Community Server.
Oct 07 22:05:47 ubuntu-s-1vcpu-512mb-10gb-nyc1-01 systemd[1]: mysql.service: Scheduled restart job, restart counter is at 5.
Oct 07 22:05:47 ubuntu-s-1vcpu-512mb-10gb-nyc1-01 systemd[1]: Stopped MySQL Community Server.
Oct 07 22:05:47 ubuntu-s-1vcpu-512mb-10gb-nyc1-01 systemd[1]: mysql.service: Start request repeated too quickly.
Oct 07 22:05:47 ubuntu-s-1vcpu-512mb-10gb-nyc1-01 systemd[1]: mysql.service: Failed with result 'oom-kill'.
Oct 07 22:05:47 ubuntu-s-1vcpu-512mb-10gb-nyc1-01 systemd[1]: Failed to start MySQL Community Server.