In this demonstration we present a preference-aware relational query answering system, termed PrefDB. The key novelty of PrefDB is the use of an extended relational data model and algebra that allow expressing different flavors of preferential queries. Furthermore, unlike existing approaches that either treat the DBMS as a black box or require modifications of the database core, PrefDB's hybrid implementation enables operator-level query optimizations without being obtrusive to the database engine. We showcase the flexibility and efficiency of PrefDB using PrefDBAdmin, a graphical tool that we have built aiming at assisting application designers in the task of building, testing and tuning queries with preferences. © 2012 ACM.