Windows平台

net stop mysql
mysqld --skip-grant-tables 
#阻塞
#换个终端
mysql
> use mysql;
> update user set password = password('xxxx') where user = 'root';
> flush privileges;
> exit;
#关闭mysqld --skip-grant-tables 终端
net start mysql

Linux平台

# systemctl stop mysqld
修改配置文件添加 --skip-grant-tables 
# vim /etc/my.cnf 在[mysqld]下面添加
    skip-grant-tables
# systemctl start mysqld
# mysql
> use mysql;
> update user set password = password('xxxx') where user = 'root';
> flush privileges;
> exit;
# systemctl stop mysqld
修改配置文件取消 --skip-grant-tables
# systemctl start mysqld