This paper investigates insider threat in relational

database systems. It discusses the problem of inferring unauthorized

information by insiders and proposes methods to

prevent such threats. The paper defines various types of

dependencies as well as constraints on dependencies that

may be used by insiders to infer unauthorized information. It

introduces the constraint and dependency graph (CDG) that

represents dependencies and constraints. In addition, CDG

shows the paths that insiders can follow to acquire unauthorized

knowledge.