For years, remove and reinstall MySQL has been one of the hardest work for me. However, I’ve found a good solution.

Based on http://askubuntu.com/questions/763534/cannot-reinstall-mysql-server-after-its-purge and http://askubuntu.com/questions/760724/16-04-upgrade-broke-mysql-server

1. Back up your my.cnf file in /etc/mysql and remove it
2. Remove the folder /etc/mysql/mysql.conf.d/
3. Verify you don’t have a my.cnf file stashed somewhere else (I did in my home dir!) or in /etc/alternatives/my.cnf.
4. Backup and remove /etc/mysql/debian.cnf files (not sure if needed, but just in case)

   sudo apt purge mysql-server mysql-server-5.7 mysql-server-core-5.7
   sudo apt install mysql-server
   

5. In case your syslog shows an error like “mysqld: Can’t read dir of ‘/etc/mysql/conf.d/'” create a symbolic link ln -s /etc/mysql/mysql.conf.d /etc/mysql/conf.d Then the service should be able to start with service mysql start.

sudo apt-get purge mysql-server mysql-client mysql-common mysql-server-core-5.7 mysql-client-core-5.7
sudo rm -rf /etc/mysql /var/lib/mysql
sudo apt-get autoremove
sudo apt-get autoclean

 

Then reboot, reinstall. Everything’s finally fine.

 

Here is a script.

 

rm /etc/mysql/my.cnf
rm -rf /etc/mysql/mysql.conf.d/
rm /etc/alternatives/my.cnf
rm /etc/mysql/debian.cnfsudo apt-get purge mysql-server mysql-client mysql-common mysql-server-core-5.7 mysql-client-core-5.7
sudo rm -rf /etc/mysql /var/lib/mysql
sudo apt-get autoremove
sudo apt-get autoclean
reboot
#After reboot:
apt-get install mysql-server