Extending the entity-relationship model to capture dynamic behaviour

The entity-relationship data model is extended by structural integrity constraints. For each entity and relationship, a list of update operations is defined, together with appropriate integrity rules. These rules are defined according to the localisation principle, which states that an update operation performed on any object in the schema should directly affect only those objects in its immediate vicinity. The update, once started, propagates through the database, respecting local integrity rules for each affected object. The integrity rules are used for algorithmic design of integrity-preserving update procedures, to be utilised in database application programs, instead of the primitive update operations supported by the DBMS itself. These procedures may be generated directly from the specification, opening the way to an automated design tool.