MySQL Security - Is there an easy way to encrypt a confidential data and also that it cannot view or access by DBA?
Traditionally this is done using a multi-tier architecture where the Application tier performs encryption before storing data in the Database tier.  The database administrators have access to dump all the data, but they don't have the keys.  The application administrators have the keys, but can't dump all the data out of the database.  Logging and auditing helps ensure that the application administrators don't try to extract mass data using their limited access.