如何将PHP版本和MySQL升级到最新的稳定版本？

I'm using google computer engine running on Debian GNU/Linux 8 with PHP version 5.6.30-0 and MySQL version 5.5.54 installed.

I would to upgrade my PHP software to v7 and mysql to v5.6.

I tried the following command, but it isn't working:

    sudo apt-get upgrade

    sudo apt-add-repository ppa:ondrej/php

any ideas?