# wget https://dev.mysql.com/get/mysql-apt-config_0.8.6-1_all.deb
# dpkg -i mysql-apt-config_0.8.6-1_all.deb
# apt update# apt-cache policy mysql-server
mysql-server:
Installed: (none)
Candidate: 5.7.20-1debian9
Version table:
5.7.20-1debian9 500
500 http://repo.mysql.com/apt/debian stretch/mysql-5.7 amd64 Packages
5.5.9999+default 500
500 http://ftp.us.debian.org/debian stretch/main amd64 Packages