常用步骤：

1. 在my.ini中的mysqld下添加一行 

skip-grant-tables

2.重启mysql后直接进入后，用SQL直接修改password列:

C:\> net stop mysql C:\> net start mysql

C:\> mysql mysql> mysql> use mysql Database changed mysql> UPDATE user SET Password=PASSWORD('newpassword') where USER='root'; ERROR 1054 (42S22): Unknown column 'Password' in 'field list'

3. 但失败了，原因是新版的mysql（5.7以后版本）这个列已经改成了"authentication_string", 所以在会失败，正确的做法是

mysql> UPDATE user SET authentication_string=PASSWORD('newpassword') where USER='root';Query OK, 1 row affected, 1 warning (0.00 sec)Rows matched: 1  Changed: 1  Warnings: 1mysql>

4. 从my.ini中去掉之前加入的skip-grant-tables那行， 然后重启mysql后，就可以用带password的root登录了

E:\mysql>net stop mysqlMySQL 服务正在停止.MySQL 服务已成功停止。E:\mysql>net start mysqlMySQL 服务正在启动 .MySQL 服务已经启动成功。E:\mysql>mysql -u root -pEnter password: ***********Welcome to the MySQL monitor.  Commands end with ; or \g.Your MySQL connection id is 2Server version: 5.7.15Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql>

5. 这个时候还没完，你还需要在正常模式下再修改一次密码，否则啥也做不了，如下错误：

mysql> use mysqlERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.

5. 而且提示很坑爹， 你必须用SET_PASSWORD， 而不是提示所说的ALTER USER

mysql> SET PASSWORD = PASSWORD('newpassword');Query OK, 0 rows affected, 1 warning (0.00 sec)mysql>use mysqlmysql>Database changed