Privacy is today an important concern for both users and enterprises. Therefore, intense research is today being carried out on various aspects of privacy-preserving data management systems. In this paper, we focus on database management systems (DBMS) able to enforce privacy promises encoded in privacy languages such as P3P. In particular, in the paper, we first present an overview of the P3P language and outlines some of its critical aspects. We then outline the main requirements for a privacy-preserving DBMS and we discuss solutions related to the management of privacy-related meta-data, focusing on special category of meta-data information, that is, purpose information. Purpose information represents an important component of privacy statements and thus their effective management is crucial. We then discuss current solutions to to fine-grained access control in the context of relational database systems and identify relevant issues.