How to install mysql on debian?

Question

MySQL

For the first time I encountered setting up a server, I realized that it would not be easy, but I did not think that I would encounter a problem at the very first stage.
After I logged in as root in the console I enter

sudo apt-get install mysql-server libapache2-mod-auth-mysql php5-mysql

to which I receive an "unknown command" in response.
There are hundreds of manuals and the same number of commands for installing a standard set on a server on the Internet, but none of the commands suited me.
The server is running Debian 8.5 x64

Answer 1

and why sudo if you are logged in as root