1.安装Mysql5.7
也可参考官方手册：https://dev.mysql.com/doc/mysql-apt-repo-quick-guide/en/#apt-repo-fresh-install
方法：手动安装5.7
One: $ wget http://dev.mysql.com/get/mysql-apt-config_0.6.0-1_all.deb
下载对应的.deb包到本服务器上
Two: $ sudo dpkg -i mysql-apt-config_0.6.0-1_all.deb
安装 确认是mysql-5.7[高亮]，选择Apply。
Three: sudo apt-get update
Four: sudo apt-get install mysql-server
上述来源于：https://www.digitalocean.com/community/tutorials/how-to-install-mysql-on-ubuntu-14-04