1 修改配置文件
vim /etc/my.cnf
[mysqld]
skip-grant-tables #添加此条配置，用来跳过授权表
2 重启数据库
systemctl restart mysqld
3 设置新密码
mysql5.6
update user set password=PASSWORD('新密码') where user='root';
mysql5.7
update user set authentication_string = password('新密码') where user = 'root';
或者
update user set authentication_string = password('新密码'), password_expired = 'N', password_last_chang_changed = now() where user = 'root';