彻底删除mysql

service mysql stop
killall -KILL mysql mysqld_safe mysqld
apt --yes purge mysql-server mysql-client
apt --yes autoremove --purge
apt autoclean
deluser --remove-home mysql
delgroup mysql
rm -rf /etc/apparmor.d/abstractions/mysql /etc/apparmor.d/cache/usr.sbin.mysqld /etc/mysql /var/lib/mysql /var/log/mysql* /var/log/upstart/mysql.log* /var/run/mysqld

安装mysql

apt install mysql-server
service mysql stop
rm -rf /var/lib/mysql
mkdir /var/lib/mysql    
chown mysql:mysql /var/lib/mysql
chmod 700 /var/lib/mysql

nano /etc/mysql/mysql.conf.d/mysqld.cnf
[mysqld]
lower_case_table_names = 1
bind-address = 0.0.0.0

mysqld --defaults-file=/etc/mysql/my.cnf --initialize --lower_case_table_names=1 --user=mysql --console
service mysql start

grep 'temporary password' /var/log/mysql/error.log
mysql -u root -p
ALTER USER 'root'@'localhost' IDENTIFIED BY '123456';
create user 'root'@'%' identified by '123456';
GRANT all privileges ON *.* TO 'root'@'%';
flush privileges;
exit;