mysql8安装后如何修改root密码

 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

ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '123456';