mysql忘记root密码解决办法：

mysql 5.7以上版本，该密码的变量为authentication_string=password('xxxxx')

>update user set authentication_string=password('123456') where user='root';

另外alter user改密码的命令为：

> alter user root@'localhost' identified by ‘xxxxx’;

SET PASSWORD命令为：

> SET PASSWORD for root@'localhost'=password('xxxxxx');

# vi /etc/mysql/my.cnf  (在[mysqld]下添加)按a或i进入编译模式skip-grant-tables按Esc键退出编译模式:wq （保存并退出）# service mysql restart# mysql> show databases;>use mysql;>update user set password=password('123456') where user='root';  （将root密码改为123456）>flush privileges;>quit# vi /etc/mysql/my.cnf  (在[mysqld]下，将添加的再注释掉)按a或i进入编译模式#skip-grant-tables按Esc键退出编译模式:wq （保存并退出）# service mysql restart# mysql -u root -p123456