在执行 sudo apt-get update时出现如下错误：
E: Malformed entry 1 in list file /etc/apt/sources.list.d/sql-server.list (Component)
E: The list of sources could not be read.
则进入/etc/apt/sources.list.d/文件夹，sudo vim sql-server.list打开文件，将下面语句注释即可：
deb [arch=amd64] https://packages.microsoft.com/ubuntu/16.04/mssql-serverxenial main
deb [arch=amd64] https://packages.microsoft.com/ubuntu/16.04/prod xenial main