Entity-relationship diagrams (ERDs)
An ERD is a graphical model that shows relationships among system entities
Each entity is a rectangle, labelled with a noun
Each relationship is a diamond, labelled with a verb
Types of relationships
One-to-one (1:1)
One-to-many (1:M)
Many-to-many (M:N)
A full ERD shows all system relationships
Explain the following tools for documenting and modelling user requirements Entity-relationship diagrams (ERDs)
