首先，用mysqldump

注意:如果您想稍后恢复，只需备份您的相关数据库，而不是整个数据库，因为整个数据库实际上可能是您需要清除和重新安装的原因).

Note: If you want to restore later, just backup your relevant databases, and not the WHOLE, because the whole database might actually be the reason you need to purge and reinstall).

总的来说，这样做:

sudo service mysql stop  #or mysqld
sudo killall -9 mysql
sudo killall -9 mysqld
sudo apt-get remove --purge mysql-server mysql-client mysql-common
sudo apt-get autoremove
sudo apt-get autoclean
sudo deluser -f mysql
sudo rm -rf /var/lib/mysql
sudo apt-get purge mysql-server-core-5.7
sudo apt-get purge mysql-client-core-5.7
sudo rm -rf /var/log/mysql
sudo rm -rf /etc/mysql

以上所有命令都在一行中(只需复制和粘贴):

sudo service mysql stop && sudo killall -9 mysql && sudo killall -9 mysqld && sudo apt-get remove --purge mysql-server mysql-client mysql-common && sudo apt-get autoremove && sudo apt-get autoclean && sudo deluser mysql && sudo rm -rf /var/lib/mysql && sudo apt-get purge mysql-server-core-5.7 && sudo apt-get purge mysql-client-core-5.7 && sudo rm -rf /var/log/mysql && sudo rm -rf /etc/mysql