ubuntu 18.04 卸載 mysql 過程記錄

20190418 爲了測試 Docker LNMP 學習環境，卸載掉之前已經安裝的 mysql

參考：
https://blog.csdn.net/iehadoop/article/details/82961264
https://www.cnblogs.com/hupeng1234/p/7003543.html

人家寫的很詳細了，我這裏記錄一下我自己的操作過程

1. 停止 mysql 服務
   sudo service mysql status
   sudo service mysql stop

2. 查詢 mysql 依賴
   :~$ dpkg --list|grep mysql

    ii  dbconfig-mysql                        2.0.9                                      all          dbconfig-common MySQL/MariaDB support
    ii  mysql-client-5.7                      5.7.25-0ubuntu0.18.04.2                    amd64        MySQL database client binaries
    ii  mysql-client-core-5.7                 5.7.25-0ubuntu0.18.04.2                    amd64        MySQL database core client binaries
    ii  mysql-common                          5.8+1.0.4                                  all          MySQL database common files, e.g. /etc/mysql/my.cnf
    ii  mysql-server                          5.7.25-0ubuntu0.18.04.2                    all          MySQL database server (metapackage depending on the latest version)
    ii  mysql-server-5.7                      5.7.25-0ubuntu0.18.04.2                    amd64        MySQL database server binaries and system database setup
    ii  mysql-server-core-5.7                 5.7.25-0ubuntu0.18.04.2                    amd64        MySQL database server binaries
    ii  php-mysql                             1:7.2+60ubuntu1                            all          MySQL module for PHP [default]
    ii  php7.2-mysql                          7.2.15-0ubuntu0.18.04.2                    amd64        MySQL module for PHP
   

3. 逐個卸載
   sudo apt-get remove mysql-common
   出錯了！

    The following packages have unmet dependencies:
     	dbconfig-mysql : Depends: default-mysql-client but it is not going to be installed or
                               virtual-mysql-client
    E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.
   

   sudo apt-get autoremove --purge mysql-server-5.7
   sudo apt-get autoremove --purge mysql-server-core-5.7
   sudo apt-get autoremove --purge mysql-client-5.7
   sudo apt-get autoremove --purge mysql-client-core-5.7
   再來
   sudo apt-get remove mysql-common

4. 清除殘留
   dpkg -l |grep ^rc|awk ‘{print $2}’ |sudo xargs dpkg -P

   sudo apt autoremove

   我這裏沒有什麼數據，使用認爲以下必要刪除
   sudo rm -rf /etc/mysql/ /var/lib/mysql
   實際環境下還是小心爲好！