You can use the new Office Web Apps 2013 Server not only for opening/viewing documents from SharePoint 2013 but also to open files directly from a URL or a file share. The link has to look like the following:
http://webappsserver/op/view.aspx?src=<UNC Path to file or URL of file>
If you do not want to build the path manually, there is a web page that does the generation of the URL or the <embed>-Code for you:
http://webappsserver/hosting -> redirects to: http://webappsserver/op/generate.aspx
Important: Make sure that the machine account of the web apps machine has the appropriate rights on the file share or URL!
My thoughts and findings about SharePoint 2016/2013/2010 and SQL Server