Navicat连接 Mysql 8.0 出现1251- Client does not support authentication protocol

百度原因是：mysql8 之前的版本中加密规则是mysql_native_password,而在mysql8之后,加密规则是caching_sha2_password, 

解决问题方法：把mysql用户登录密码加密规则还原成mysql_native_password. 

ALTER USER 'root'@'localhost' IDENTIFIED BY '123456' PASSWORD EXPIRE NEVER; #修改加密规则 

ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '123456'; #更新一下用户的密码