添加用户：
insert into mysql.user(Host,User,Password,ssl_cipher,x509_issuer,x509_subject) values ("192.168.186.1","allen",password("allen"),'','','');
刷新：
flush privileges;
授权：
grant select on test.* to 'allen'@'192.168.186.1';
刷新：
flush privileges;
查看授权情况
SHOW GRANTS FOR allen@192.168.186.1;
删除用户：
DROP USER allen@192.168.186.1;
