The project aims to effectively and efficiently analysing uncertain data in large-scale applications. Uncertain data are inherent in a wide range of real applications. In this project, we will develop, analyse, implement and evaluate novel techniques to effectively analyse complex uncertain data by probabilistic queries. Specifically, we will develop novel techniques to precisely model and efficiently process seriously important probabilistic queries with a primary focus on the applications where probability distributions of objects are independent to each other. We will also support the applications where uncertain data may be dynamically updated by developing on-line data analysis techniques.