之前在電腦里安裝了MySQL57之后，一直沒用，卻忘記了root密碼，
在網上找了一些資料修改root密碼，卻一直出錯。直到試到這個：
用管理員權限打開CMD
CD C:Program FilesMySQLMySQL Server 5.7in
net stop mysql57
mysqld --skip-grant-tables
再另外打開一個管理員權限的CMD
CD C:Program FilesMySQLMySQL Server 5.7in
mysql
mysql> use mysql
mysql> update mysql.user set authentication_string=PASSWORD('yourpassword') where user='root';
mysql> flush privileges;
mysql> quit
Bye
OK，用新密碼登陸即可：
C:Program FilesMySQLMySQL Server 5.7in>mysql -u root -p
Enter password: ************
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 10
Server version: 5.7.15 MySQL Community Server (GPL)
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or 'h' for help. Type 'c' to clear the current input statement.
mysql>