1. Database
Dr. Roueida Mohammed

2. The Entity Relationship Model
The entity relationship model (or ER model) is a way of graphically representing the logical relationships of entities (or objects) in order to create a database.

3. Elements of the E/R Model
Entity sets.
Attributes.
Relationships

4. Entity-Relationship Diagrams
An E/R diagram is a graph representing entity sets, attributes, and relationships. Elements of each of these kinds are represented by nodes of the graph, and we use a special shape of node to indicate the kind, as follows:
Entity sets are represented by rectangles.
Attributes are represented by ovals.
Relationships are represented by diamonds

5. RELATIONSHIP SETS
one-to-one
one-to-many
many-to-one
Many-to-many

6. Design Principles Faithfulness Avoiding Redundancy Simplicity Counts
Choosing the Right Relationships
Picking the Right Kind of Element

7. The Modeling of Constraints
Keys
Single-value constraints
Referential integrity constraints
Domain constraints
General constraints

8. Weak Entities