Download the MySQL APT repository config tool (you can see more details and the latest version of the tool here: http://dev.mysql.com/downloads/repo/apt/)

wget https://dev.mysql.com/get/mysql-apt-config_0.8.9-1_all.deb

Install the MySQL APT repository config tool

dpkg -i mysql-apt-config_0.8.9-1_all.deb

You will be asked to select product and version that you want to install. In the first step, select Server and next select either mysql-5.6 or mysql-5.7. Then click Apply.

Update APT

apt-get update

Install the server

apt-get install mysql-server

Set the data directory in /etc/mysql/mysql.conf.d/mysqld.cnf, restart the server and run the table upgrade utility

/etc/init.d/mysql restart
mysql_upgrade -u<user> -p

Uninstall mysql with

sudo apt-get remove --purge mysql\*

Install APT repository sources

sudo apt-get install software-properties-common
sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 0xcbcb082a1bb943db
sudo add-apt-repository 'deb [arch=amd64,i386,ppc64el] http://www.ftp.saix.net/DB/mariadb/repo/10.1/debian  jessie main'

Install MariaDB server

sudo apt-get update
sudo apt-get install mariadb-server

Install phpmyadmin and php5-mysql which got uninstalled when uninstalling mysql

apt-get install phpmyadmin

Modify configuration file /etc/mysql/my.cnf and set path to data directory

Restart server and run mysql-upgrade

/etc/init.d/mysql restart
mysql-upgrade

login to the server (command line or phpmyadmin) and set the password of user debian-sys-maint to the one stored in /etc/mysql/debian.cnf

Install MySQLTuner

wget https://github.com/major/MySQLTuner-perl/tarball/master
tar xf master
cd major-MySQLTuner-perl-993bc18/
./mysqltuner.pl