Covert list item attachement files to SQL binary field

I have a SharePoint list that contains attachment files. Now, I am writing C# code to transfer the SharePoint list to a SQL table. I am not sure how to transfer the attached files to binary data for the SQL table. I google on the web and see most the solution are how to get the files URLs and export them to a windows folder.  However, I need to open/access each file then convert them to Binary. Thank you very much for any suggestion.