Entity relationship diagrams (ERDs) are a graphical representation of entities and their relationships in a database. ERDs were developed in 1976 by Peter Chen and introduced by Charles Bachman. An ERD uses objects, attributes, and relationships to model how data is connected. Relationships can be one-to-one, one-to-many, or many-to-many. Cardinality and modality are also expressed to define maximum numbers and whether relationships are optional or mandatory.

1. Entity
Relationship
Diagram
Presented by:
Muhammad umer
Bs(cs) 4th (b)

2. Entity relationship
diagram
* In 1976 Peter Chen was developed ERD
* Introduce by Charles Bachman
* A Graphical Representation
* A Semantic Data model

3. COMPONENTS OF ERD
* Data objects
* Data attributes
* Relationship

4. TYPES OF
RELATIONSHIP
* One to One
* One to Many
* Many to Many

5. ONE TO ONE
ROOF
COVERS
COVERD BY
BUILDING

6. ONE TO MANY
EMPLOYEE
WORK IN
HAS
DEPARTMENT

7. MANY TO MANY
EQUIPMENT
ALLOCATED TO
ALLOCATED
PROJECT

8. CARDINALITY & MODALITY
* Cardinality:
Express the maximum number of
relationships
* Modality:
Express whether the relationships is
optional or mandatory

9. THANK
YOU