【Linux】【Mysql】ERROR 1698 (28000): Access denied for user ‘root‘@‘localhost‘

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Tools ：
mysql Ver 14.14 Distrib 5.7.25, for Linux (x86_64)

Problem description ：
Ubuntu Upon completion of installation mysql after , No direct access mysql -u root -p Command login mysql, The following error occurred ：ERROR 1698 (28000): Access denied for user ‘root’@‘localhost’

resolvent ：

Ubuntu linux Install new version under mysql, When installing root The code is random , Therefore, the above error occurs .

First step , Sign in mysql

Since we can't pass root User access MySQL, Then we can only log in through other users MySQL 了 . After we download and install MySQL The system creates a user for us . open /etc/mysql/debian.cnf as follows .

[email protected]:~$ sudo cat /etc/mysql/debian.cnf

[email protected]:~$ sudo cat /etc/mysql/debian.cnf 
# Automatically generated for Debian scripts. DO NOT TOUCH!
[client]
host     = localhost
user     = debian-sys-maint
password = 0NBFUVaaRF8KiZBD
socket   = /var/run/mysqld/mysqld.sock
[mysql_upgrade]
host     = localhost
user     = debian-sys-maint
password = 0NBFUVaaRF8KiZBD
socket   = /var/run/mysqld/mysqld.sock

We find client Of user and password, Then input... At the terminal
mysql -u debian-sys-maint -p
And then enter password The content of . This is the way to enter MySQL 了 , Pictured ：

[email protected]:~$ mysql -u debian-sys-maint -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.38-0ubuntu0.18.04.1 (Ubuntu)

Copyright (c) 2000, 2022, Oracle and/or its affiliates.

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.

The second step , see user surface

stay mysql Input in ：

select user, plugin from mysql.user,

give the result as follows ：

+------------------+-----------------------+
| user             | plugin                |
+------------------+-----------------------+
| root             | auth_socket           |
| mysql.session    | mysql_native_password |
| mysql.sys        | mysql_native_password |
| debian-sys-maint | mysql_native_password |
+------------------+-----------------------+
4 rows in set (0.00 sec)

The third step , modify root password

Enter the following command , among 123456 It's a password ：

update mysql.user set authentication_string=PASSWORD('123456'), plugin='mysql_native_password' where user='root';

mysql> update mysql.user set authentication_string=PASSWORD('123456'), plugin='mysql_native_password' where user='root';
Query OK, 1 row affected, 1 warning (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 1

Step four , Refresh

Enter the following command ：

flush privileges;

Then restart the server , You can log in normally

sudo service mysql restart

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