Presentation: Entity Relationship Diagrams (ERD) (x11 slides)

The presentation introduces the idea of data redundancy (repeating data) inside tables. It shows using clear diagrams how to avoid this by splitting a table into two separate tables and introducing a one to many relationship between these two tables. It goes onto show how to represent ‘many to many’ relationships using two ‘one to many’ relationships, before defining the two important keys; primary and foreign key.

There is a word document worksheet where the pupils have to describe the relationships between entities.