Entity Relationship Model (ER model) in DBMS

January 25, 2023

ER Model in DBMS

In DBMS, the entity-relationship (ER) model is a way of representing data in a conceptual view. It is used to design and model a database and its components, such as entities, attributes, and relationships.

Entity-Relationship model (ER model)

An effective system where data is organized into discrete categories called entities(different database tables)
ERmodel is an illustration of various entities in business and the relationship between them
It is built during the analysis phase of the system development life cycle
The ER model separates the information required in the business i.e it establishes a clear distinction between data that is useful and not useful for business operations

What is Database

Participation Constraint

DBMS Architecture

Data Models

Cardinality

Key components of the ER model

Entity :

It is a set of related information i.e nothing but a database table.

Attributes :

- It defines what type of data an entity is storing i.e different columns in a table
- For example, a student entity consists of student name, ID, marks as attributes
- An entity may contain any numbers of attribute but it must contain at least one attribute .

Relationships :

- It is defined as an association between entities links between different database tables for data accessing
- Several relationships may exist between the same entity basically 4 relationships are identified
  - One to one
  - One to many
  - Many to one
  - Many to many

- These relationships are nothing but the links between in a table to another table or set of tables so that data can be transferred and used from more than one table .

ER model benefits

Provide a clear picture of the scope of information requirement
Provides an easily understandable pictorial map for database design
It offers an effective Framework for integrating multiple applications.

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