A transaction-based approach to relational database specification

Abstract

An operational approach to database specification is proposed and investigated. Valid database states are described as the states resulting from the application of admissible transactions, specified by a transactional schema . The approach is similar in spirit to the modeling of behavior by methods and encapsulation in object-oriented systems. The transactions considered are line programs consisting of insertions, deletions, and modifications, using simple selection conditions. The results concern basic properties of transactional schemas, as well as the connection with traditional constraint schemas. In particular, the expressive power of transactional schemas is characterized. Although it is shown that transaction-based specification and constraint-based specification are incomparable, constraints of practical interest that have corresponding transactional schemas are identified. The preservation of constraints by transactions is also studied.