mysql5.7.9之后，就没有了password函数，所以，使用传统的password()函数修改root密码的话，就会提示sql错误
UPDATE user SET authentication_string = password(‘123456‘) WHERE User=‘root‘; ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘(‘123456‘) WHERE User=‘root‘‘ at line 1
正确设置密码的方法是：
ALTER USER ‘root‘@‘localhost‘ IDENTIFIED WITH mysql_native_password BY ‘123456‘;
此时提示修改成功，退出mysql再次登陆即需要输入刚刚设置的密码。
具体请参考文章：
https://newsn.net/say/mysql8-password.html
原文：https://www.cnblogs.com/saysmy/p/11135369.html