On the relational representation of complex specialization structures

摘要

The mapping of entity-relationship schemas (ER schemas) that contain complex specialization structures into the relational model requires the use of specific strategies to avoid inconsistent states in the final relational database. In this paper, we show that for this mapping to be correct it is required to enforce a special kind of integrity constraint, the key pairing constraint (KPC). We present a mapping strategy that use simple inclusion dependencies to enforce KPC and show that this strategy can be used to correctly map specialization structures that are more general than the simple specialization structures considered by previous strategies.