查表对应的主键:
select index_name,column_name, from information_schema.statistics where table_schema='mysql' and table_name='user';
查看用户信息：
select user,hostname from mysql.user where user='root';
查看当前用户信息：
mysql -e 'select current_user()'
文件输入：
sudo bash -c 'echo "192.168.18.227 client_a">>/etc/hosts'
创建用户：
create user narisu@client_a identified by narisu;
查看客户端主机信息：
select host from information_schema.processlist;
修改密码：
alter user narisu@locahost identified by 'newpasswd';
set password for narisu@locahost ='newpassword';
alter user user() identified by 'newpasswd';
set password='newpassword';
mysqladmin -u narisu -p password 'newpassword';

密码过期参数：default_password_lifetime
8.0.14 开始有一个账户设置两个密码，更改主密码后辅助密码可以在副本上登录，经过一段时间后手工抛弃旧密码
alter user narisu@localhost identified by 'narisu_new' retain current password;
alter user narisu@localhost discard old pasword;