1, modify the mysql configuration file, implement password-free login
在mysql配置文件中添加以下参数：
[mysqld]
skip-grant-tables
2, restart the MySQL service
service mysqld restart
3, free secret landing
mysql -uroot -p (直接点击回车，密码为空)
4, change the root password
1.切换数据库
use mysql;
2.执行命令修改密码
update user set password=password('root') where user='root';
//5.7 以后版本执行上面命令报错可以尝试以下语句：
update user set authentication_string=password('123456') where user='root';
3.刷新权限
flush privileges;
//可能会出现的异常
ERROR 1820 (HY000): You must reset your password using ALTER USER statement；
//解决办法（执行以下命令）：
alter user user() identified by "root";
5, restore the configuration file, restart the Mysql service
[mysqld]
#skip-grant-tables
//重启服务
service mysqld restart
