Deriving Relationships between Integrity Constraints for Schema Comparison

Schema comparison is essential for integrating diierent database schemata. Since the semantics of a schema is also represented by its integrity constraints, they must be considered by a correct schema comparison method. Especially the extensional relationships between classes are determined by the relationship between the corresponding integrity constraint sets. In this paper, we work out the relationships between diierent types of integrity constraints. As a result, we present rules for comparing integrity constraint sets. These rules can be used after a schema conforming step, where naming, type and structural connicts are solved, to exactly x the extensional relationship between object classes.