The document discusses different data models used in databases including the relational model and entity-relationship model. It provides details on: - The relational model represents data as relations and was first described by Edgar Codd in 1969 using tuples grouped into tables. It includes concepts like attributes, tables, tuples, relations and keys. - The entity-relationship model is a high-level data model used to define data elements and relationships. It develops a conceptual design for the database using entity-relationship diagrams where entities can have attributes and relationships between entities are represented. - Components of an ER diagram include entities, attributes, relationships and notations to show cardinality. The ER diagram can then be reduced to a collection

1. Different data models
Relational model & E-R model
Submitted by-
1. Samriddhi Sarkar (121-1211-0738-19)
2. Anubrata Sarkar (121-1111-0719-19)
3. Sanjoy Sarkar (121-1112-0739-19
Gour Mahavidyalaya
Date : 03/06/2021
Session : 4th semester (2019-20)
Department of computer science & application

2. What is Data Models?
Data Model is the modeling of the data description,
data semantics, and consistency constraints of the
data. It provides the conceptual tools for describing
the design of a database at each level of data
abstraction.

3. -:Types of database models:-
● Hierarchical database model
● Relational model
● Network model
● Object-oriented database
model
● Entity-relationship model
● Document model
● Entity-attribute-value model
● Star schema
● The object-relational model
There are many kinds of data models. Some of the most common ones include-

4. -: Relational Model :-
Relational Model (RM) represents the database as a collection of relations.
first described in 1969 by English computer scientist Edgar F. Codd, where all data is
represented in terms of tuples, grouped into relations.

5. Primary key Foreign key
-:Linking relation table:-

6. -: Relational Model Concepts :-
● Attribute
● Tables
● Tuple
● Relation Schema
● Degree
● Cardinality Column
● Relation instance
● Relation key
● Attribute domain

7. -: Types of Relational operation :-
σ p(r) ∏ A1, A2,
An (r)
R ∪ S R ∩ S R - S E X D ρ(S1, S)

8. -: Entity-Relationship model :-
● ER model stands for an Entity-Relationship model. It is a high-
level data model. This model is used to define the data
elements and relationship for a specified system.
● It develops a conceptual design for the database. It also
develops a very simple and easy to design view of data.
● In ER modeling, the database structure is portrayed as a
diagram called an entity-relationship diagram.

9. For example, Suppose we design a school database. In this database, the
student will be an entity with attributes like address, name, id, age, etc. The
address can be another entity with attributes like city, street name, pin code, etc
and there will be a relationship between them.

10. -: Component of ER Diagram :-

11. A. Weak Entity
● Entity

12. ● Attribute
1. Key Attribute:- 2. Composite
Attribute :-
3. Multivalued Attribute:- 4. Derived Attribute:-

13. ● Relationship:-
a. One-to-One Relationship
b. One-to-many relationship
c. Many-to-one relationship
d. Many-to-many relationship

14. -: Notation of ER diagram:-
Database can be represented using the notations. In ER diagram, many notations are used to
express the cardinality. These notations are as follows:

15. -: Reduction of ER diagram to Table :-
The database can be represented using the notations, and these notations can be reduced to a
collection of tables. In the database, every entity set or relationship set can be represented in tabular
form.
The ER diagram is given below:

16. There are some points for converting the ER diagram to the table:
● Entity type becomes a table.
● All single-valued attribute becomes a column for the table.
● A key attribute of the entity type represented by the primary
key.
● The multivalued attribute is represented by a separate table.
● Composite attribute represented by components.
● Derived attributes are not considered in the table.

17. Using these rules, you can convert the ER diagram to tables and columns and assign the mapping
between the tables. Table structure for the given ER diagram is as below:

18. Source:
1. DBMS Tutorial | Database Management System - javatpoint
2. Database System Concepts 6th Edition, A. Silberschatz, H.F. Korth, S. Sudarshan,McGraw Hill.
Anyone have any question?
Thank you
for your attention.