Building data base management systems through formal specification

Abstract

Using the ANSI/SPARC concept of a three level architecture for data base management systems, a relational data base system is formally specified. The formal specification technique used is VDM and it is illustrated how the various VDM features contribute to a concise but in its abstraction level easily adjustable description. At first the external conceptual and internal levels and their data manipulation languages are discussed separately. Then the mapping properties of the data base management system which has to transform external user requests into their internal executable form are investigated. In practice many restrictions are placed on the insert and update operations that can be used on the external view of the data base system. Through our formal specification, we are able to show that many of these restrictions can be relaxed without violating the integrity, security and consistency constraints of the DBMS.