Despite a rich set of techniques designed to process specific types of optimization queries such as top-k, skyline, NN/kNN and dominant relationship analysis queries, a unified system for a general process of such kinds of queries has not been addressed in the literature. In this paper, we propose PDA, a interactive personal decision assistant system, for people to get the desired optimal decision easily. In addition to supporting the basic queries mentioned above, PDA can also support some sophisticated queries. Several novel technologies are employed to improve the flexibility and efficiency of the system and a visualization interface like google map is provided for people to view the query result interactively.