Formal semantics for database schemas

摘要

We propose an abstract semantics for database schemas which considers the interaction between the disjointness and the “is-a” relationships between data types. Our approach is based on a system of axioms introduced and proven sound and complete by Atzeni and Parker.By introducing the concept of mergeable family of schemas we propose a design methodology of database schemas whose goal is to generate schemas which are free of inconsistencies and redundancy.We also investigate the generalization and specialization methods of abstraction as a useful tool in the specification of database semantics using as a staring point the conditions formulated by Abiteboul and Hull for the IFO model when the disjointness constraints are present.