Jonathan Kehayias gives us a set of features we can use to secure data in SQL Server:
Recently I have been having quite a few discussions around security of data inside of SQL Server and how to prevent the massive data breaches that we have been hearing about on the news. Like most things some people want “THE ANSWER” or THE SOLUTION to securing the data inside of SQL Server. Unfortunately there isn’t a single solution that solves all of the problems that are potentially out there. Security of data requires defense in depth, starting with a secure configuration and installation of SQL Server. Often times, defense in depth also means changes to the database, the application, and how you do business.
Also read the comments to understand why Dynamic Data Masking and Row-Level Security aren’t really security features. I totally agree that Dynamic Data Masking is not a security feature; Row-Level Security I’d argue is, but is quite limited in its scope, much more so than any of the features Jonathan lists.