1. Conceptual Data Modeling
Concept of ERD
Entity Relationship Diagram (ERD) is building block of Relational Database Design
It was developed by Peter Chain in 1976

2. Conceptual Data Modeling
Concept of ERD
It is end result of Systematic process to visualize Business data not Business Process
Its is graphical representation of relationship between things in System

3. Conceptual Data Modeling
Concept of ERD
It is end result of Systematic process to visualize Business data not Business Process
Its is graphical representation of relationship between things in System

4. Conceptual Data Modeling
Components of ERD
Entity
Attributes
Relationships

5. Conceptual Data Modeling
Entity and Attributes
Word is rooted from Latin word “en” meaning being.
Entity is name of place, person or thing about which something can be stored in a system

6. Conceptual Data Modeling
Entity and Attributes
Attribute are those qualities or data about Entities to be stored.
#: Primary Key
* : Mandatory
0: Optional

7. Conceptual Data Modeling
Relationships
To reduce redundancy in databases , relationships are created between entities
Interaction among entities are captures using relationships

8. Conceptual Data Modeling
Relationships
Relationship is bi-directional
It consist of Optionality (O) and Cardinality (C)
R=O + C

9. Conceptual Data Modeling
Optionality
Minimum child records that can exist per parent record
It can be Zero or One
Zero is represented by (dotted line)
One by Solid line

10. Conceptual Data Modeling

11. Conceptual Data Modeling

12. Conceptual Data Modeling
Cardinality
Maximum child records that can exist per parent record
It can be One or more
Represented by < , >

13. Conceptual Data Modeling
Cardinality
Cardinality is read with opposite entity

14. Conceptual Data Modeling

15. Conceptual Data Modeling

16. Conceptual Data Modeling
One to Many Relationship
This is basic relationship
One record of parent entity (table) having zero or more occurrence in child entity (table)

17. Conceptual Data Modeling
One to Many Relationship
Primary key of parent table is referenced in Child Table as Foreign Key

18. Conceptual Data Modeling

19. Conceptual Data Modeling

20. Conceptual Data Modeling

21. Conceptual Data Modeling
Many to Many Relationship
This is basic not a relationship
Third table is created where primary keys of both table are exported as foreign keys

22. Conceptual Data Modeling
Many to Many Relationship
One to many is resolved into Two One to Many relationships

23. Conceptual Data Modeling

24. Conceptual Data Modeling

25. Conceptual Data Modeling
One-to-One
This is A basic relationship
There is no parent and child table
There is exactly one matching record in two tables

26. Conceptual Data Modeling
One-to-One
Primary key of any table exported as Foreign key in any one table
Foreign is made is Unique Key

27. Conceptual Data Modeling

28. Conceptual Data Modeling
Implementing ERD using Scenario – 1

29. Implementing ERD using Scenario – 1
In a Building – Apartment renting scenario, there are Apartment, building and customer. There are multiple floors in the building and on each floor there are multiple apartments, floor can have zero or no apartment. Each apartment can be rented at most one customer but customer can rent out multiple apartments from same building and apartment can be available on multiple floor or same. At the end of month a recipe is generated against which a rent is deposited

30. Implementing ERD using Scenario – 1

31. Conceptual Data Modeling
Implementing ERD using Scenario – II

32. Implementing ERD using Scenario – 1
There are musical bands which record songs and request musical companies to launch their songs in the form of Album. Songs are written by song writers. Album can contain at least one song to be album and max of 12 songs. Writer can write multiple songs but songs are usually written irrespective of the number of person in the bands.

33. Implementing ERD using Scenario – 1