In order to avoid getting answers that you already know won't work, please expand the question to add more details: Did you try with sudo apt install and got any errors? If not, how do you conclude that mysql-server cannot be installed that way? Is there any other method you tried?

Yes you're right. I was a bit not comfortable with this question because I think that mysql-server is not available in the Debian package distribution but I'm not sure (because I'm quite a newbie on Debian and Unix systems in general). I edited the question after your comment, please tell me if you think it needs more clarifications...