遇到修改mysql用户命令不成功时，可通过下面命令进行检查，在mysql的安装路径执行命令：
1）安装mysqld
E:\mysql-8.0.12-winx64\bin>mysqld --initialize --console
E:\mysql-8.0.12-winx64\bin>mysqld --install
2）启动mysql服务
E:\mysql-8.0.12-winx64\bin>net start mysql
3）查看mysql服务是否存在
E:\mysql-8.0.12-winx64\bin>tasklist| findstr "mysql"
4）进入mysql数据库，输入原密码
E:\mysql-8.0.12-winx64\bin>mysql -u root -p
5）修改密码
mysql> ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '123456';
Query OK, 0 rows affected (0.02 sec)
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.01 sec)
修改密码时的解释
ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password'; #更新一下用户的密码
FLUSH PRIVILEGES; #刷新权限
