1、修改密码：
use mysql;
update user set password=password('new_password') where user='root';
update user set authentication_string=password('new_password') where user='root'; //mysql 5.7
flush privileges;
创建用户并授权撤权：
create user 'imooc'@'%' identified by '123456';
grant all privileges on *.* to 'imooc'@'%' identified by "123456" with grant option;
grant select on *.* to 'imooc'@'%' identified by "123456" with grant option;
revoke all privileges on *.* from imooc;//撤权
flush privileges;
忘记数据库root密码，方法：在配置文件/etc/my.cnf中添加skip-grant-tables，重启mysql服务。直接登入修改密码后，再注释掉skip-grant-tables，重启mysql服务。
2、删除MySQL命令历史：
cd ~
echo > .mysql_history
3、记录mysql操作命令
使用mysql -uroot -p,进入mysql终端,执行下面命令：
set global general_log_file="/tmp/general.log";
set global general_log=on
