Entity relationship diagram Name: Quian Crosby Form:6AQ Subject: Information Technology Teacher: Ms. D. Anderson

What is an Entity Relationship Diagram? An entity-relationship (ER) diagram is a specialized graphic that illustrates the interrelationships between entities in a database.

What are the symbols used in ERD? There are three basic elements in ER models: Entities are the "things" about which we seek information. Attributes are the data we collect about the entities. Relationships provide the structure needed to draw information from multiple entities.

What is a one-one relationship? One-to-one relationships occur when there is exactly one record in the first table that corresponds to exactly one record in the related table.

What is a one-many relationship? One-to-many relationships occur when each record in Table A may have many linked records in Table B but each record in Table B may have only one corresponding record in Table A.

What is a many-many relationship?. In a "many to many“ relationship, one record in either table can relate to many records in the other table