sudo apt remove --purge mysql-server* mysql-common
sudo apt autoremove --purge
sudo rm -r /etc/mysql
sudo rm -r /var/lib/mysql

$ mysql --version
bash: /usr/bin/mysql: No such file or directory

$ sudo apt update

$ sudo apt install mysql-server

$ sudo mysql_secure_installation

Securing the MySQL server deployment.

Connecting to MySQL using a blank password.

VALIDATE PASSWORD COMPONENT 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 component?

Press y|Y for Yes, any other key for No: 

There are three levels of password validation policy:

LOW    Length >= 8
MEDIUM Length >= 8, numeric, mixed case, and special characters
STRONG Length >= 8, numeric, mixed case, special characters and dictionary                  file

Please enter 0 = LOW, 1 = MEDIUM and 2 = STRONG: 

Skipping password set for root as authentication with auth_socket is used by default.
If you would like to use password authentication instead, this can be done with the "ALTER_USER" command.
See https://dev.mysql.com/doc/refman/8.0/en/alter-user.html#alter-user-password-management for more information.

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) : 

Remove anonymous users? (Press y|Y for Yes, any other key for No) : 

ormally, 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) : 

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) : 

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) : 

$ sudo mysql
[sudo] password for username: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 10
Server version: 8.0.35-0ubuntu0.22.04.1 (Ubuntu)

Copyright (c) 2000, 2023, 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.

mysql> 

$ mysql -u root -p
Enter password: 
ERROR 1698 (28000): Access denied for user 'root'@'localhost

mysql> SHOW VARIABLES LIKE 'validate_password%';
+-------------------------------------------------+-------+
| Variable_name                                   | Value |
+-------------------------------------------------+-------+
| validate_password.changed_characters_percentage | 0     |
| validate_password.check_user_name               | ON    |
| validate_password.dictionary_file               |       |
| validate_password.length                        | 8     |
| validate_password.mixed_case_count              | 1     |
| validate_password.number_count                  | 1     |
| validate_password.policy                        | LOW   |
| validate_password.special_char_count            | 1     |
+-------------------------------------------------+-------+
8 rows in set (0.00 sec)

mysql> SELECT user, host FROM mysql.user;
+------------------+-----------+
| user             | host      |
+------------------+-----------+
| debian-sys-maint | localhost |
| mysql.infoschema | localhost |
| mysql.session    | localhost |
| mysql.sys        | localhost |
| root             | localhost |
+------------------+-----------+

mysql> SELECT user,authentication_string,plugin,host FROM mysql.user;
+------------------+------------------------------------------------------------------------+-----------------------+-----------+
| user             | authentication_string                                                  | plugin                | host      |
+------------------+------------------------------------------------------------------------+-----------------------+-----------+
| debian-sys-maint | $A$005$L|/?c8ohX%e:]WTu5nnUoZId9OSqu.ubi2d6KU3qSn09f6sqokrW3AeV9 | caching_sha2_password | localhost |
| mysql.infoschema | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password | localhost |
| mysql.session    | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password | localhost |
| mysql.sys        | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password | localhost |
| root             |                                                                        | auth_socket           | localhost |
+------------------+------------------------------------------------------------------------+-----------------------+-----------+

mysql > CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';

mysql > CREATE DATABASE databasename;

mysql> show grants for 'you'@'localhost';
+----------------------------------------+
| Grants for you@localhost                |
+----------------------------------------+
| GRANT USAGE ON *.* TO `you`@`localhost` |
+----------------------------------------+

mysql > grant all on *.* to username@localhost;

pymysql.err.OperationalError: (1044, "Access denied for user 'you'@'localhost' to database 'testk'")