| In the past few decades, the increase of computers in almost any domain has caused an increase in the generation of data. As the information explosion has grown, data sharing and information exchange has also grown. So, more and more data is being shared amoung different kinds of users doing different kinds of jobs, residing in different different places, for different kinds of applications. Privacy control is a major issue for todays' data managers.;A multilevel database system is a database management system in which the data has different classifications and the users have different security clearances and authorizations. The problem of inference exists in a multilevel database if knowledge of some objects in the database allows information with a higher security level to be inferred. This violates the whole purpose of a multilevel database system in which the user is not supposed to know any information higher than his security clearance. So, the problem of inference should always be considered while designing a multilevel database system.;The current solutions for inference control lack simplicity and are difficult to implement. In this thesis, we present three models built upon each other to solve query aggregation inference problem. |
