# make sure the following lines are in your /etc/apt/sources.list
deb http://packages.dotdeb.org jessie all
deb-src http://packages.dotdeb.org jessie all
# install multibyte string support, its php7 version, native language support (and mysqli extension if not already installed with mysql)
# mysql is removed from PHP7, php7.0-mysql is in fact mysqli
sudo apt-get install php-mbstring php7.0-mbstring php-gettext php7.0-mysql
# install PHPMyadmin
apt-get install phpmyadmin
# create symbolic link from phpmyadmin.conf to /etc/phpmyadmin/apache.conf
sudo ln -s /etc/phpmyadmin/apache.conf /etc/apache2/[conf.d|conf-available]/phpmyadmin.conf