mysql8 增加用户

create database xxxx_db;
 create user 'username'@'%' identified by 'xxxxxxx'; 
 grant all privileges on xxxxx_db.* to 'username'@'%' ; 
 flush privileges; 

drop user 'username'@'%';

ALTER USER 'username'@'%' IDENTIFIED WITH mysql_native_password BY 'xxxxxxx';