Hey this is all about data base

1. Database Management
Entity – Relationship (ER) Diagram
Prof. Sridhar Vaithianathan

2. DATA MODELING
A Data Model is a map or diagram that
represents entities and their relationships.

7. Some Definitions
 A File/Entity/Table: A group or collection of
similar records
 A record / Tuple: one piece of data, i.e., one
student's information, a recipe, a test question.
 Records = rows
 A field/Attributes: one category of information,
i.e., Name, Address, Semester Grade, Academic
topic
 (Fields = columns)

8. ER Diagram - Example

16. CARDINALITY AND MODALITY

17. Entity Relationship Diagram - Notation
Entitiy
Relationship
Associated Object
Mandatory (Exactly) One
Optional (Zero or one) One
Mandatory Many
Optional Many
Optional
Mandatory

18. E – R Diagram Example
Basket Ball Game
Entities:
Home Stadium
Team
Player
Games

19. ER – Diagram Example – Basket Ball Game
HOME
STADIUM TEAM
PLAYER
Has
Has
GAME
Participates
Has

20. Entities, Attributes and Relationship
 Strong Entity Vs Weak entity ( EMPLOYEE &
DEPENDENT)
 Simple Vs Composite Attributes
 Single Valued Vs Multi Valued Attributes
 Stored Vs Derived Attributes
 Identifier Attribute – Primary Key
 Composite Identifier
 Foreign Key
 Sub-Type Vs Super Type Relationship

21. Database Associations Example
HOME STADIUM
Stadium Id Stadium Name, Capacity, Location
TEAM
Team Id Team Name
PLAYER
Player Id Player Name, Position
GAME
Team id(1) Team id(2) Date Final Score
B
A
S
K
E
T
B
A
L
L
G
A
M
E

22. Relationship Example Instructions
One-to-One.
TEAM
Team Id Team Name,
Stadium Id
Each team has only one home
stadium, and each home
stadium has only one team.
STADIUM and TEAM
Place the primary key from
one entity to other entity as a
foreign key and vice versa.
(i.e. foreign key can be placed
at either side of the
relationship.)
One-to-Many
PLAYER
Player Id Player
Name, Position, Team Id
Each player is on only one
team, but each team has many
players.
PLAYER and TEAM
Place the primary key from
the entity on the one side of
the relationship as a foreign
key in the table for the entity
on the many side of the
relationship
Many-to-Many
PLAYER STATISTICS
Team id(1), Team id(2), Date,
Player Id Points
Each player participates in
many games and each game
has many players.
PLAYER and GAME
Create a third entity/table and
place the primary keys from
each of the original entities
together in the third table as a
combination primary key
DATABASE ASSOCIATIONS …

23. ER – Diagram : Basket Ball Game
HOME
STADIUM TEAM
GAME
STATISTICS
PLAYER
GAME
Has
Partici
-pates Has
Has
Has

24. ERD Development Process
 Identify the entities
 Determine the attributes for each entity
 Select the primary key for each entity
 Establish the relationships between the
entities
 Draw an entity model
 Test the relationships and the keys

25. THANKS
THANKS
THANKS
THANKS
THANKS