Uncertain data are inherent in some important applications, such as environmental surveillance, market analysis, and quantitative economics research. Due to the importance of those applications and the rapidly increasing amount of uncertain data collected and accumulated, analyzing large collections of uncertain data has become an important task and has attracted more and more interest from the database community. Recently, uncertain data management has become an emerging hot area in database research and development. In this tutorial, we systematically review some representative studies on answering various queries on uncertain and probabilistic data. Categories and Subject Descriptors H.2.4 [Database Management]: Systems General Terms Algorithm, Performance Keywords Uncertain Data, Probabilistic data, Query processing