8. MAPPING AN ERD TO A RELATIONAL DATABASE
We use an Entity Relationship Diagram to represent the informational needs of a system. When we are convinced it is satisfactory, we map the ERD to a relational database and implement as a physical database.
In general, relations are used to hold entity sets and to hold relationship sets. The considerations to be made are listed below. After we present the mapping rules, we illustrate their application in a few examples.