报错内容如下： 

Mar 05 18:40:49 VM-0-12-centos systemd[1]: Failed to start MySQL Server.
Mar 05 18:40:49 VM-0-12-centos systemd[1]: Unit mysqld.service entered failed state.
Mar 05 18:40:49 VM-0-12-centos systemd[1]: mysqld.service failed.
Mar 05 18:40:49 VM-0-12-centos systemd[1]: mysqld.service holdoff time over, scheduling restart.
Mar 05 18:40:49 VM-0-12-centos systemd[1]: start request repeated too quickly for mysqld.service
Mar 05 18:40:49 VM-0-12-centos systemd[1]: Failed to start MySQL Server.
Mar 05 18:40:49 VM-0-12-centos systemd[1]: Unit mysqld.service entered failed state.
Mar 05 18:40:49 VM-0-12-centos systemd[1]: mysqld.service failed.

解决方案：

1.查看/etc/my.cnf中日志记录，查看错误

2.如果日志为空，使用journalctl -xe查看系统日志，要一直往上翻，找报error的地方，然后再次百度修改错误。这个很重要很重要。

修改错误后，将日志文件，数据文件都清空。

再重新启动。