Про XML и MS SQL

http://djekmusic.blogspot.ru/2012/07/xml-microsoft-sql-server-2008-xml.html
http://djekmusic.blogspot.ru/2012/07/xml-microsoft-sql-server-2008-xml_17.html
http://djekmusic.blogspot.ru/2012/07/xml-microsoft-sql-server-2008-xml_23.html

https://social.msdn.microsoft.com/Forums/en-US/58c1b27d-3274-4942-962c-06ff0671661b/how-to-use-entity-frame-work-with-xml-fields-in-relational-database?forum=adodotnetentityframework

и про джейсон
http://blogs.msdn.com/b/jocapc/archive/2015/05/16/json-support-in-sql-server-2016.aspx