Uninstall mysql and delete cache
sudo apt purge mysql-*
sudo rm -rf /etc/mysql/ /var/lib/mysql
sudo apt autoremove
sudo apt autoclean
Reinstall
sudo apt-get install mysql-server -y
Check if the mysql service starts successfully
sudo netstat -tap | grep mysql
The output should look like this

If mysql is not started, run the start command
sudo service mysql start
Warning: cannot change directory to xxx...

The solution reference is as follows:
If need password for root user
In special cases, you need to enter the root password. However, we first logged in and did not have the root user password
1. Get password for default user
sudo cat /etc/mysql/debian.cnf

2. Log in with the default user and password found above
mysql -udebian-sys-maint -pRkqm8f6NHv1CYsrB
