Lecture 5 Flashcards
1
Q
What are the type of relations in an ER model?
A
- Entity and enitity sets
- Attributes
- Relationships
2
Q
What is an ER-diagram?
A
A diagram with nodes and connecting verices
3
Q
What do the nodes represent in an ER diagram?
A
Entity sets: rectangles
Attributes: ovals
Relationships: diamonds
4
Q
What kind of edges are in an ER-diagram?
A
Normal edges: Between ES and attribute, or ES and relationship if relationship is ‘many-many’
Arrow: from relationship to ES fro ‘many-one’ and ‘one-one’ case
5
Q
What does ES stand for?
A
Entity sets
