This SQL ER Diagram for Streaming Movies is a visual tool representing the ER model. In 1971, Peter Chen proposed the ER Diagram as a uniform convention for relational databases and networks. As a conceptual modeling approach, he intended to use an ER model. Entity Relationship Diagram Symbols & Notations primarily use three basic symbols to represent relationships between elements, commodities, and attributes: rectangle, oval, and diamond. In the ERD Diagram, some sub-elements are based on the main aspects. The ER Diagram is a visual demonstration of data that describes how data relates to one another using various ERD Symbols and Notations.