Difference between ER diagram and EER diagram
问题 What is the difference between ERD (Entity relationship diagram) and EERD (enhanced entity relationship diagram)? 回答1: Entity-Relationship model You have relationships (image source) and attributes (image source) that can also be primary keys (image source) Enhanced entity–relationship model You have the same as with the ER model plus specialisation partitioning (which are multiple specialisations) generalisation aggregation keys are annotated differently: 回答2: I would add that ER model is