Ubuntu20默认安装mysql8，需要mysql5.7环境进行c/c++程序开发，安装步骤：
一、换源
1、备份源
sudo cp /etc/apt/sources.list /etc/apt/sources.list.old
2、更新源
sudo vi /etc/apt/sources.list
清空原内容，将以下代码粘贴进去：
#阿里云源 deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse ##測試版源 deb http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse # 源碼 deb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse ##測試版源 deb-src http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse # Canonical 合作夥伴和附加 deb http://mirrors.aliyun.com/ubuntu/ xenial partner deb http://mirrors.aliyun.com/ubuntu/ xenial main #清华源 deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main restricted universe multiverse deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main restricted universe multiverse deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse ##測試版源 deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse # 源碼 deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main restricted universe multiverse deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main restricted universe multiverse deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse ##測試版源 deb-src http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse # Canonical 合作夥伴和附加 deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial partner deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main
3、更新源和软件：
# 更新镜像源 sudo apt-get update # 更新软件 sudo apt-get upgrade
二、安装mysql5.7和开发包，按照以下步骤：
sudo apt-get install libtinfo5 sudo apt-get install mysql-client-core-5.7 sudo apt-get install mysql-client-5.7 sudo apt-get install mysql-server-5.7 sudo apt install libmysqlclient-dev
过程中需要确认一次卸载，输入两次口令。
安装完成后查看版本：
mysql -V
完成。
