//设置密码初始密码
update mysql.user set authentication_string = password('root'), plugin = 'mysql_native_password' where user = 'root';

//授权
grant all privileges on user_db.* to 'user_name'@'%' identified by 'user_password';
grant all privileges on user_db.* to 'user_name'@'%' identified by 'user_password' with grant option;