Ubuntu安装MySQL的三种方式以及卸载MySQL

删除mysql的数据文件
sudo rm /var/lib/MySQL/ -R

删除mysql的配置文件
sudo rm /etc/mysql/ -R

自动卸载mysql（包括server和client）
sudo apt-get autoremove mysql* --purge
sudo apt-get remove apparmor

检查是否卸载干净
dpkg -l | grep mysql# 若没有返回，说明已完成卸载

dpkg --list|grep mysql  #首先在终端中查看MySQL的依赖项
sudo apt-get remove mysql-common #卸载
sudo apt-get autoremove --purge mysql-server-8.0 #卸载，看你自己安装的什么版本在卸载
dpkg -l|grep ^rc|awk '{print$2}'|sudo xargs dpkg -P  #清除残留数据
dpkg --list|grep mysql   #再次查看MySQL的剩余依赖项，基本到这就干净了
sudo apt-get autoremove --purge mysql-apt-config  #如果有的话继续删除剩余依赖项

sudo apt update && sudo apt upgrade
sudo su #进入特权模式，使用的是root权限，这样后续执行命令就不需要sudo
apt install -y mysql-server #安装的是最新版本，比如MySQL8.0的
mysql -V  #查看版本
mysql -uroot  #这种安装方式前期没有设置密码，直接登录

cat /etc/mysql/debian.cnf

ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '新密码';

dpkg -i mysql-common_8.0.20-2ubuntu20.04_amd64.deb
dpkg -i mysql-community-client-core_8.0.20-2ubuntu20.04_amd64.deb
dpkg -i mysql-community-client_8.0.20-2ubuntu20.04_amd64.deb

dpkg -i mysql-community-server-core_8.0.20-2ubuntu20.04_amd64.deb #这里应该会报错，缺少依赖，缺啥补啥
apt install -y libmecab2  #安装依赖，这里是我缺的依赖
dpkg -i mysql-community-server-core_8.0.20-2ubuntu20.04_amd64.deb

dpkg -i mysql-client_8.0.20-2ubuntu20.04_amd64.deb
dpkg -i mysql-community-server_8.0.20-2ubuntu20.04_amd64.deb

mysql -V 
mysql -uroot -p123

wget https://dev.mysql.com/get/Downloads/MySQL-5.7/mysql-boost-5.7.18.tar.gz
tar -zxvf mysql-5.7.18.tar.gz

apt install -y cmake bison libncurses5-dev build-essential

cd mysql-5.7.18/
cmake -DCMAKE_INSTALL_PREFIX=/usr/local/mysql -DMYSQL_DATADIR=/usr/local/mysql/data -DWITH_BOOST=boost
make && make install

groupadd mysql
useradd -g mysql mysql
mkdir /usr/local/mysql/data
chown -R mysql /usr/local/mysql
chgrp -R mysql /usr/local/mysql

/usr/local/mysql/bin/mysqld --initialize --user=mysql --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data

vim /etc/my.cnf
//添加下面的内容
[client]
socket = /tmp/mysql.sock
 
[mysqld]
port=3306
socket = /tmp/mysql.sock
basedir = /usr/local/mysql
datadir = /usr/local/mysql/data

cp /usr/local/mysql/support-files/mysql.server /etc/init.d/mysqld
chmod +x /etc/init.d/mysqld
update-rc.d mysqld defaults
service mysqld start
service mysqld status #确定已经启动

ln -s /usr/local/mysql/bin/mysql /usr/bin/mysql
mysql -uroot -p'（udyv%Tmv0#e'

//重新修改密码 为123456
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY '123456';
exit 退出

mysql>GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY '123456' WITH GRANT OPTION;
mysql>flush privileges;
exit