首先执行以下命令:

sudo mysql

然后你应该检查你的MySQL用户帐户使用的身份验证方法。运行这个命令

SELECT user,authentication_string,plugin,host FROM mysql.user;

现在你可以看到这样的东西:

+------------------+-------------------------------------------+-----------------------+-----------+
| user             | authentication_string                     | plugin                | host      |
+------------------+-------------------------------------------+-----------------------+-----------+
| root             |                                           | auth_socket           | localhost |
| mysql.session    | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | mysql_native_password | localhost |
| mysql.sys        | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | mysql_native_password | localhost |
| debian-sys-maint | *CC744277A401A7D25BE1CA89AFF17BF607F876FF | mysql_native_password | localhost |
+------------------+-------------------------------------------+-----------------------+-----------+

在上面的表格中，你可以看到你所有的mysql用户的帐户状态&如果你已经设置了root帐户的密码，然后在插件列中看到mysql_native_password而不是auth_socket。 总之，要更改root密码，您应该运行以下命令:

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

请务必将密码更改为您选择的强密码。 然后重新加载你的服务器，把你的新变化生效运行这个;

FLUSH PRIVILEGES;

所以再次检查你的mysql所使用的认证方法，通过下面的命令:

SELECT user,authentication_string,plugin,host FROM mysql.user;

现在输出是:

+------------------+-------------------------------------------+-----------------------+-----------+
| user             | authentication_string                     | plugin                | host      |
+------------------+-------------------------------------------+-----------------------+-----------+
| root             | *3636DACC8616D997782ADD0839F92C1571D6D78F | mysql_native_password | localhost |
| mysql.session    | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | mysql_native_password | localhost |
| mysql.sys        | *THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE | mysql_native_password | localhost |
| debian-sys-maint | *CC744277A401A7D25BE1CA89AFF17BF607F876FF | mysql_native_password | localhost |
+------------------+-------------------------------------------+-----------------------+-----------+

正如您在授权表中看到的，您的根帐户具有mysql_native_password ． 现在你可以退出MYSQL shell了

exit;

就是这样。只是你应该通过sudo service mysql restart重新启动mysql。 现在你可以用root帐号和密码轻松登录mysql。

该任务指导用户在Ubuntu操作系统下设置/修改/重置MySQL root密码。在终端中输入以下行。

停止MySQL服务器:sudo /etc/init.d / mysql停止 (在某些情况下，如果/var/run/mysqld不存在，你必须首先创建它:sudo mkdir -v /var/run/mysqld && sudo chown mysql /var/run/mysqld 启动mysqld配置:sudo mysqld——skip-grant-tables & 以root身份登录MySQL: MySQL -u root MySQL 用你的新密码替换YOURNEWPASSWORD:

MySQL < 8.0

UPDATE mysql.user SET Password = PASSWORD('YOURNEWPASSWORD') WHERE User = 'root';
FLUSH PRIVILEGES;

如果你的MySQL使用新的认证插件，你将需要使用:update user set plugin="mysql_native_password" where user ='root';在冲洗特权之前。

注意:在某些版本，如果密码列不存在，你可能想尝试: UPDATE user SET authentication_string=password('YOURNEWPASSWORD') WHERE user='root';

注意:这种方法不是最安全的重置密码的方法，但它是有效的。

对于MySQL >= 8.0

FLUSH PRIVILEGES;
ALTER USER 'root'@'localhost' IDENTIFIED BY 'YOURNEWPASSWORD';
FLUSH PRIVILEGES;

最后一步:

正如@lambart的评论中所提到的，你可能需要杀死你启动的临时无密码mysql进程，即sudo killall -9 mysqld，然后启动正常的守护进程:sudo service mysql start

引用:

该任务指导用户在Ubuntu Linux下设置/修改/重置MySQL root密码 如何重置Root用户密码(v5.6) 如何重置Root用户密码(v8.0)

如果部署在xampp上，您可以通过提供的phpadmin gui轻松更改mysql密码。

phpMyAdmin -> User Accounts -> Edit Privileges (Select the intended user) -> Change Password (Tab)

对于mysql 5.6，这个命令有效，你可以通过向导设置密码:

sudo dpkg-reconfigure mysql-server-5.6

这就像我为Ubuntu 16.04做的一样。 完全归功于下面的链接，因为我从那里得到了它。 [https://coderwall.com/p/j9btlg/reset-the-mysql-5-7-root-password-in-ubuntu-16-04-lts] [1]

停止MySQL

sudo service mysql stop

制作MySQL服务目录。 Sudo mkdir /var/run/mysqld

赋予MySQL用户写入服务目录的权限。

sudo chown mysql: /var/run/mysqld

手动启动MySQL，不需要权限检查或联网。

sudo mysqld_safe --skip-grant-tables --skip-networking &

无需密码即可登录。

mysql -uroot mysql

更新root用户密码。 确保下面的查询至少更新了根帐户。 如果您愿意，进行一些选择并检查现有的值

UPDATE mysql.user SET 
authentication_string=PASSWORD('YOURNEWPASSWORD'), 
plugin='mysql_native_password' WHERE User='root';
EXIT;

关闭MySQL。

sudo mysqladmin -S /var/run/mysqld/mysqld.sock shutdown

正常启动MySQL服务。

sudo service mysql start

I had to go this route on Ubuntu 16.04.1 LTS. It is somewhat of a mix of some of the other answers above - but none of them helped. I spent an hour or more trying all other suggestions from MySql website to everything on SO, I finally got it working with: Note: while it showed Enter password for user root, I didnt have the original password so I just entered the same password to be used as the new password. Note: there was no /var/log/mysqld.log only /var/log/mysql/error.log Also note this did not work for me: sudo dpkg-reconfigure mysql-server-5.7 Nor did: sudo dpkg-reconfigure --force mysql-server-5.5 Make MySQL service directory. sudo mkdir /var/run/mysqld Give MySQL user permission to write to the service directory. sudo chown mysql: /var/run/mysqld Then:

kill the current mysqld pid run mysqld with sudo /usr/sbin/mysqld & run /usr/bin/mysql_secure_installation Output from mysql_secure_installation root@myServer:~# /usr/bin/mysql_secure_installation Securing the MySQL server deployment. Enter password for user root: VALIDATE PASSWORD PLUGIN can be used to test passwords and improve security. It checks the strength of password and allows the users to set only those passwords which are secure enough. Would you like to setup VALIDATE PASSWORD plugin? Press y|Y for Yes, any other key for No: no Using existing password for root. Change the password for root ? ((Press y|Y for Yes, any other key for No) : y New password: Re-enter new password: By default, a MySQL installation has an anonymous user, allowing anyone to log into MySQL without having to have a user account created for them. This is intended only for testing, and to make the installation go a bit smoother. You should remove them before moving into a production environment. Remove anonymous users? (Press y|Y for Yes, any other key for No) : y Success. Normally, root should only be allowed to connect from 'localhost'. This ensures that someone cannot guess at the root password from the network. Disallow root login remotely? (Press y|Y for Yes, any other key for No) : y Success. By default, MySQL comes with a database named 'test' that anyone can access. This is also intended only for testing, and should be removed before moving into a production environment. Remove test database and access to it? (Press y|Y for Yes, any other key for No) : y Dropping test database... Success. Removing privileges on test database... Success. Reloading the privilege tables will ensure that all changes made so far will take effect immediately. Reload privilege tables now? (Press y|Y for Yes, any other key for No) : y Success. All done!