https://www.digitalocean.com/community/tutorials/how-to-install-mysql-on-ubuntu-18-04

siddjain@engblog:~$ sudo apt update
Hit:1 http://azure.archive.ubuntu.com/ubuntu bionic InRelease
Get:2 http://azure.archive.ubuntu.com/ubuntu bionic-updates InRelease [88.7 kB]
Get:3 http://azure.archive.ubuntu.com/ubuntu bionic-backports InRelease [74.6 kB]
Get:4 http://security.ubuntu.com/ubuntu bionic-security InRelease [88.7 kB]
Get:5 http://azure.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages [753 kB]
Get:6 http://azure.archive.ubuntu.com/ubuntu bionic-updates/main Translation-en [271 kB]
Get:7 http://azure.archive.ubuntu.com/ubuntu bionic-updates/restricted amd64 Packages [15.7 kB]
Get:8 http://azure.archive.ubuntu.com/ubuntu bionic-updates/restricted Translation-en [4956 B]
Get:9 http://azure.archive.ubuntu.com/ubuntu bionic-updates/universe amd64 Packages [1012 kB]
Get:10 http://azure.archive.ubuntu.com/ubuntu bionic-updates/universe Translation-en [312 kB]
Get:11 http://azure.archive.ubuntu.com/ubuntu bionic-updates/multiverse amd64 Packages [7884 B]
Get:12 http://azure.archive.ubuntu.com/ubuntu bionic-updates/multiverse Translation-en [3944 B]

siddjain@engblog:~$ sudo apt install mysql-server
Unpacking libcgi-fast-perl (1:2.13-1) …
Selecting previously unselected package libencode-locale-perl.
Preparing to unpack …/07-libencode-locale-perl_1.05-1_all.deb …
Unpacking libencode-locale-perl (1.05-1) …
Selecting previously unselected package libhtml-template-perl.
Preparing to unpack …/08-libhtml-template-perl_2.97-1_all.deb …
Unpacking libhtml-template-perl (2.97-1) …
Selecting previously unselected package libtimedate-perl.
Preparing to unpack …/09-libtimedate-perl_2.3000-2_all.deb …
Unpacking libtimedate-perl (2.3000-2) …
Selecting previously unselected package libhttp-date-perl.
Preparing to unpack …/10-libhttp-date-perl_6.02-1_all.deb …
Unpacking libhttp-date-perl (6.02-1) …
Selecting previously unselected package libio-html-perl.
Preparing to unpack …/11-libio-html-perl_1.001-1_all.deb …
Unpacking libio-html-perl (1.001-1) …
Selecting previously unselected package liblwp-mediatypes-perl.
Preparing to unpack …/12-liblwp-mediatypes-perl_6.02-1_all.deb …
Unpacking liblwp-mediatypes-perl (6.02-1) …
Selecting previously unselected package libhttp-message-perl.
Preparing to unpack …/13-libhttp-message-perl_6.14-1_all.deb …
Unpacking libhttp-message-perl (6.14-1) …
Selecting previously unselected package mysql-server.
Preparing to unpack …/14-mysql-server_5.7.27-0ubuntu0.18.04.1_all.deb …
Unpacking mysql-server (5.7.27-0ubuntu0.18.04.1) …
Setting up libhtml-tagset-perl (3.20-3) …
Setting up libevent-core-2.1-6:amd64 (2.1.8-stable-4build1) …
Setting up libencode-locale-perl (1.05-1) …
Setting up libtimedate-perl (2.3000-2) …
Setting up libio-html-perl (1.001-1) …
Setting up liblwp-mediatypes-perl (6.02-1) …
Setting up libaio1:amd64 (0.3.110-5ubuntu0.1) …
Setting up liburi-perl (1.73-1) …
Setting up libhtml-parser-perl (3.72-3build1) …
Setting up libcgi-pm-perl (4.38-1) …
Setting up mysql-client-core-5.7 (5.7.27-0ubuntu0.18.04.1) …
Setting up libfcgi-perl (0.78-2build1) …
Setting up libhttp-date-perl (6.02-1) …
Setting up libhtml-template-perl (2.97-1) …
Setting up mysql-server-core-5.7 (5.7.27-0ubuntu0.18.04.1) …
Setting up libcgi-fast-perl (1:2.13-1) …
Setting up libhttp-message-perl (6.14-1) …
Setting up mysql-client-5.7 (5.7.27-0ubuntu0.18.04.1) …
Setting up mysql-server-5.7 (5.7.27-0ubuntu0.18.04.1) …
update-alternatives: using /etc/mysql/mysql.cnf to provide /etc/mysql/my.cnf (my.cnf) in auto mode
Renaming removed key_buffer and myisam-recover options (if present)
Created symlink /etc/systemd/system/multi-user.target.wants/mysql.service → /lib/systemd/system/mysql.service.
Setting up mysql-server (5.7.27-0ubuntu0.18.04.1) …
Processing triggers for libc-bin (2.27-3ubuntu1) …
Processing triggers for systemd (237-3ubuntu10.26) …
Processing triggers for man-db (2.8.3-2ubuntu0.1) …
Processing triggers for ureadahead (0.100.0-21) …

siddjain@engblog:~$ sudo mysql_secure_installation

Securing the MySQL server deployment.

Connecting to MySQL using a blank password.

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: Y

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: 2
Please set the password for root here.

New password: enter your password for root user

Re-enter new password: re-enter the password

Estimated strength of the password: 100
Do you wish to continue with the password provided?(Press y|Y for Yes, any other key for No) : Y
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!

siddjain@engblog:~$ cat /etc/mysql/my.cnf
#
# The MySQL database server configuration file.
#
# You can copy this to one of:
# – “/etc/mysql/my.cnf” to set global options,
# – “~/.my.cnf” to set user-specific options.
#
# One can use all long options that the program supports.
# Run program with –help to get a list of available options and with
# –print-defaults to see which it would actually understand and use.
#
# For explanations see
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html

#
# * IMPORTANT: Additional settings that can override those from this file!
# The files must end with ‘.cnf’, otherwise they’ll be ignored.
#

!includedir /etc/mysql/conf.d/
!includedir /etc/mysql/mysql.conf.d/

let’s change the data directory. We have attached a 1TB disk and mounted it at /data. Let’s store our data there so that we can back it up and attach to a different VM if need be.

https://www.fromdual.com/mysql-configuration-file-sample

https://www.digitalocean.com/community/tutorials/how-to-change-a-mysql-data-directory-to-a-new-location-on-centos-7

Find the line in the [mysqld] block that begins with datadir=, which is separated from the block heading with several comments. Change the path which follows to reflect the new location. In addition, since the socket was previously located in the data directory, we’ll need to update it to the new location:

so change the file to

siddjain@engblog:~$ cat /etc/mysql/my.cnf
#
# The MySQL database server configuration file.
#
# You can copy this to one of:
# – “/etc/mysql/my.cnf” to set global options,
# – “~/.my.cnf” to set user-specific options.
#
# One can use all long options that the program supports.
# Run program with –help to get a list of available options and with
# –print-defaults to see which it would actually understand and use.
#
# For explanations see
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html

#
# * IMPORTANT: Additional settings that can override those from this file!
# The files must end with ‘.cnf’, otherwise they’ll be ignored.
#

!includedir /etc/mysql/conf.d/
!includedir /etc/mysql/mysql.conf.d/

[mysqld]

datadir=/data/mysql
socket=/var/run/mysqld/mysqld.sock

[client]
port=3306
socket=/var/run/mysqld/mysqld.sock

above is assuming you have a mysql.sock under /var/run/mysqld (you should. check it)

Now when you run mysqld –initialize you will get error:

siddjain@engblog:~$ mysqld –initialize
mysqld: Can’t create directory ‘/data/mysql/’ (Errcode: 13 – Permission denied)
2019-10-18T17:27:43.696325Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use –explicit_defaults_for_timestamp server option (see documentation for more details).
2019-10-18T17:27:43.704308Z 0 [ERROR] Aborting