Question 2

What forms the basis of an ERD?

ERM

What is optional participation?

One entity occurrence does not require corresponding entity occurrence in a particular relationship

What does an erd represent?

The conceptual database

List the 6 steps of developing an ERD

1. create narrative of organization operations 2. identify business rules 3. identify entities and relationships 4. develop initial erd 5. identify attributes and keys 6. revise and review

What are a database's main components?

Entities, attributes and relationships

What is a weak relationship?

If the PK of a related entity does not contain a PK component of the parent entity

What are cardinality and connectivity established by?

Business rules

What is a strong relationship?

When PK of related entity contains PK component of parent entity

What is mandatory participation?

One entity occurrence requires corresponding entity occurrence in particular relationship

What are the two types of relationship participation?

Optional and mandatory