Щось корисне про IT

If you want update Mysql from 5.6 to 5.7 do this steps

https://dev.mysql.com/downloads/repo/apt/

Download mysql-apt-config_0.6.0-1_all.deb

Install apt-sources

dpkg -i mysql-apt-config_0.6.0-1_all.deb

After that you have apt-resources for installing
Update resources

apt-get update

Install Mysql server

apt-get install mysql-server

And upgrade mysql tables

mysql_upgrade

Also you can use another method with repository ondrej

$ sudo apt-get install software-properties-common
$ sudo add-apt-repository -y ppa:ondrej/mysql-5.7
$ sudo apt-get update
$ sudo apt-get install mysql-server

Also read wthat new in 5.7
https://dev.mysql.com/doc/refman/5.7/en/upgrading-from-previous-series.html