Data Security in MS SQL Server
One alternative is to encrypt and decrypt in the app, and SQL server will of course have no knowledge that this data was born as anything else. Or, in SQL Server 2016, use Always Encrypted which means that the database API (ODBC, ADO.NET, JDBC...) does the job for you. Regardless of which solution, make sure that the DBA don't have access to the key. And, since the whole point is that the SQL Server never sees the clear-text data, you cannot manipulate using pure T-SQL. (In SQL Server 2019 will will have secure enclaves allowing for the database engine to decrypt the data to allow for things such as rotation of keys, LIKE, BETWEEN etc, but that isn't released yet.)