增加用户并授权：
grant select,insert,update,delete on *.* to test@"%" Identified by "aaa";
#增加一个用户test，密码为aaa，该用户可在任何主机上（%）登录，并对所有数据库（*.*所有库的所有表）有查询、插入、修改、删除的权限：
查看用户情况：
SELECT User, Host, Password FROM mysql.user;
查看某个用户权限：
show grants for ‘usertest‘;
添加用户：
create user usertest identified by ‘aaa’;
用户授权：
grant all privileges on dbtest.* to usertest@‘%‘ identified by ‘aaa‘;
flush privileges;
修改用户密码：
update mysql.user set password = password(‘newpassword‘) where user = ‘usertest‘ and host = ‘%‘;
flush privileges;
删除用户：
drop user usertest@‘%‘;
原文：https://www.cnblogs.com/lalalaya/p/10124058.html