Tools such as EdrawMax or EdrawMax Online are widely used for creating the program questions system ER diagrams. As graphically represented below, the three main components of the ER model are entities, attributes, and relationships. As the program questions, system ER diagram suggests, three types of entities are commonly used in ERD. These shapes are independent of other entities and are often called parent entities since they will often have weak entities that depend on them. It should be noted here that the primary key is a candidate key that is selected by the database designer to be used as an identifying mechanism for the whole entity set.
