This Chen ER Diagram for Doctor and Patient depicts the doctor-patient relationship using Chen notation. Chen notation is used to describe the doctor-patient relationship on an entity-relationship diagram. Entity-relationship diagrams show how data objects in a database interact with one another. A database designer can utilize an ER diagram to sketch the system's structure using only three basic elements: entities, attributes, and relationships. An ER diagram is the initial step in designing a database, and an ERD assists the designer in avoiding problems later on when building the database. An entity-relationship chart can also be used to document and analyze an existing system in the opposite direction.