说明：localhost表示本地访问，%表示全网访问

1.查询用户

$SELECT User, Host FROM mysql.user;

2.创建用户

$CREATE USER 'new_user'@'localhost' IDENTIFIED BY 'user_password';

3.给与所有库所有权限

$ GRANT ALL ON *.* TO 'huyuan'@'%';

4.给与xx库所有权限

$ GRANT ALL PRIVILEGES ON database_name.* TO 'username'@'%';

5.给与xx库xx权限

$ GRANT SELECT, INSERT ON database_name.* TO 'username'@'localhost';

6.查询所有用户所有权限

$ SELECT DISTINCT CONCAT('SHOW GRANTS FOR \'', user, '\'@\'', host, '\';') AS query FROM mysql.user;