E/R Modelling | EECS-3421-A: Introduction to Database Systems | Fall 2016

Table of Contents

Subclasses in E/R

Modelling the domain

What is your design?

Rel-ship $\Rightarrow$ relation

Combining many-one relations

Handling weak entity sets

E/R style

Attribute vs Entity

When to promote an attr. to an entity?

Cassettes

Ambiguity / missing “logic”

A better design?

One needs changing!

choice of change
Which to change?

Rel-ship vs Entity

When to promote a rel-ship to an entity?

And put it all together…