腾讯云服务器（Ubuntu18.04） MySQL 账号密码问题

用root用户连接MySQL 数据库报"ERROR 1698 : Access denied for user ‘root’@‘localhost’" 错误。

MySQL 5.7版本不能使用命令行代码mysql -u root -p进入，也不能使用直接mysql进入，但是可以通过命令sudo mysql进入，想通过mysql -u root -p可以如下解决：

$ sudo mysql -u root # I had to use “sudo” since is new installation
mysql> USE mysql;
mysql> SELECT User, plugin FROM mysql.user;
±-----------------±----------------------+
| User | plugin |
±-----------------±----------------------+
| root | auth_socket |
| mysql.sys | mysql_native_password |
| debian-sys-maint | mysql_native_password
±-----------------±----------------------+

mysql> UPDATE user SET authentication_string=PASSWORD('123456') where User='root';
mysql> UPDATE user SET plugin=‘mysql_native_password’ WHERE User=‘root’;
mysql> select host,user,plugin from user;
+-----------+------------------+-----------------------+
| host      | user             | plugin                |
+-----------+------------------+-----------------------+
| %         | root             | mysql_native_password |
| localhost | mysql.sys        | mysql_native_password |
| localhost | debian-sys-maint | mysql_native_password |
+-----------+------------------+-----------------------+
5 rows in set (0.00 sec)

mysql> FLUSH PRIVILEGES;
mysql> exit;
$ sudo service mysql restart

参考链接：MySQL-1698 : Access denied for user ‘root’@'localhost’解决方法
ERROR 1698 (28000): Access denied for user ‘root’@‘localhost’