当我使用此命令sudo apt-get install ***在我的 ubuntu 中安装新包时，mysql 总是报告此错误，有没有人可以帮助我解决这个问题，非常感谢。
0 upgraded, 0 newly installed, 0 to remove and 86 not upgraded.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Setting up mysql-server-5.7 (5.7.23-0ubuntu0.18.04.1) ...
/var/lib/mysql/ibdata1: 6982
ERROR: Database files are locked. Daemon already running?
Warning: Unable to start the server. Please restart MySQL and run mysql_upgrade to ensure the database is ready for use.
/var/lib/mysql/ibdata1: 6982
ERROR: Database files are locked. Daemon already running?
Warning: Unable to start the server.
Job for mysql.service failed because the control process exited with error code.
See "systemctl status mysql.service" and "journalctl -xe" for details.
invoke-rc.d: initscript mysql, action "start" failed.
● mysql.service - MySQL Community Server
Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
Active: activating (auto-restart) (Result: exit-code) since Thu 2018-10-11 17:12:54 CST; 14ms ago
Process: 30930 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/run/mysqld/mysqld.pid (code=exited, status=1/FAILURE)
Process: 30921 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
Main PID: 1090 (code=exited, status=0/SUCCESS)
dpkg: error processing package mysql-server-5.7 (--configure):
installed mysql-server-5.7 package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
mysql-server-5.7
E: Sub-process /usr/bin/dpkg returned an error code (1)
