Design and implementation of derivation rules in information systems

摘要

In contrast to tables and integrity constraints, database triggers have no direct equivalent in conceptual models. To enable CASE generators to create database triggers, therefore, derivation rules for entities and attributes are introduced into conceptual modeling. The necessity of an open, reusable representation of data derivation in information systems is discussed. A systematic approach to abstraction dependencies is presented that is used to specify invariants, and, subsequently, to derive generalised repair rules for most inconsistencies that are caused by deletions and insertions. Based on the proposed system of abstraction dependencies, classes of derivation rules can be identified which imply similar invariants and for which generalised propagations can be derived. Using three basic types of parametrical trigger declarations, the extended system specification is transformed into database triggers which complement the traditional schema implementation comprising tables and integrity constraints. To illustrate the proposed information system development extensions, a subschema for a MRP II-style production management system is developed using a commercial, graphical systems design tool and the proposed trigger generator.