select myql 5.7
wget wget https://dev.mysql.com/get/mysql-apt-config_0.8.12-1_all.deb
dpkg -i mysql-apt-config_0.8.12-1_all.deb
turns off the GPG check
sources.list.d/mysql.list
deb [trusted=yes] http://repo.mysql.com/apt/ubuntu/ bionic mysql-5.7
install mysql and create admin user
sudo apt update
apt-cache policy mysql-server | grep 5.7
sudo apt install mysql-client=5.7.37-1ubuntu18.04 mysql-community-server=5.7.37-1ubuntu18.04
mysql -u root -p
GRANT ALL PRIVILEGES ON *.* TO 'admin'@'%' IDENTIFIED BY 'pass' WITH GRANT OPTION