An Analysis of the Structural Validity of Unary and Binary Relationships in Entity Relationship Modeling

We explore the criteria that contribute to the validity of modeling structures within the entity-relationship (ER) diagram. Our approach examines cardinality constraints in conjunction with the degree of the relationship to address constraint consistency and role uniqueness issues. Here we use both maximum and minimum cardinality constraints yielding a complete analysis of the structural validity of unary and binary relationship types. Our study evaluates these relationships as part of the overall diagram, and our rules address these relationships as they coexist in a path structure within the model. Our analysis yields a comprehensive set of decision rules based on path connectivity to determine the structural validity of any ER diagram containing unary and binary relationships. These rules can be readily applied to real world models regardless of the complexity. They can easily be incorporated into the database modeling and design process or extended into case tool implementations.