Over the last years the means to collect personal data implicitly or explicitly over the Web and by various kinds of sensors and to combine data for profiling individuals has dramatically increased. These improved abilities have a dramatic impact on the privacy of every individual. This talk focuses on presenting and discussing techniques, concepts, and algorithms how to prevent privacy breaches when personal data is either stored or individuals are at risk to reveal which data they access. In the first part of the talk we introduce several examples of privacy breaches that help us to better understand what is at risk and to categorize the kind of privacy threads and privacy attacks. These examples will give us a better understanding of the different attacks on privacy as observed on the real world. They also show us that privacy is at risk in different fields such as in the field of communication and in the field of database systems. The latter will be the focus for the rest of the p...