Data Models in DBMS

The data models in a DBMS defines the logical design and structure of a database. It describes how data is stored, accessed and updated in a DBMS.

The first ever data model was flat type. In this all the data is stored in a sample plane. In this model there were high chances of duplication of data and update anomalies.

Different Data Models in DBMS

There are many data models in DBMS which includes

  1. Flat model
  2. Entity relationship model
  3. Relation model
  4. Record base model
  5. Network model
  6. Hierarchical model
  7. Object oriented model
  8. Object relation model
  9. Semi structured model
  10.  Associative model
  11.  Context model

Only four of these models are most popular among these 11 and are widely used. They are

  • Entity relationship model
  • Relational model
  • Network model
  • Hierarchical model

In which Relational data model is most used model in present usage.

Entity Relationship Data model

An Entity-Relationship(ER) Model is mainly based on the notion of real-world objects called entities and relationships between these entities. An ER model has entity set, relationship set, general attributes and constraints. This model is best for conceptual design of a database. The entities and relationships in an entity relationship model can be converted into tables in a relational database.

Entity Relationship model

ER model is mainly based on

  • Entities
  •  Attributes
  • Relationships

Entities

Entities in a ER model are the real world objects that has some properties or characteristics. Entities in an ER model are represented using rectangles.

Attribute

Attributes are the properties or characteristics of an entity. Attributes are represented using ellipses and are connected to entities.

Relationships

Relationship is the logical association among entities. These relationships are represented using diamond shape or rhombus shape.

Relational Data Model

Relational model is the most popular and widely used type in DBMS data models. It is more scientific than other data models in DBMS. In a relational models, data is in two-dimensional tables and the relationship is maintained by storing a common field. This is based on first-order predicate logic and defines a table as an n-ary relation.

relation in relational model

Tables are the basic structure of data in a relational database. All the information related to any particular type is stored in rows of that table. Hence, tables are also known as relations in a relational model of DBMS.

This model was introduced by E.F Codd in 1970.

Relational Data Model

Hierarchical Data Model

In hierarchical data models, data is organized into tree like structures. Which has a single root or parent to which all the other children are linked. This starts from a parent and expands by adding children to it various levels.

In hierarchical model a child will have only one parent from which it is derived.

hierarchical model

In this model, data is organized into tree-like structures with one-to-many relationship between two different types of data.

Network Data Model

Network model can be explained as an extension to the hierarchical model. In which data is organized as graphs and can have more than one parent to a child. In a network model data is more related as more relationships are established in this database model. Also, as the data is more related, accessing the data also becomes easier and faster.

Network Model

This data model was used to map many-to-many data relationships.

Before the relational model was introduced by E.F Codd this was the most widely used model.

Reference: Database Management Systems

Also Read: File system vs DBMS

Levels of abstraction in DBMS

DBMS - Data Models

How do you define a data model?

The data model in a DBMS defines the logical design and structure of a database. It describes how data is stored, accessed and updated in a DBMS.

What are the different types of data models?

There are many data models in DBMS which includes
Flat model
Entity relationship model
Relation model
Record base model
Network model
Hierarchical model
Object oriented model
Object relation model
Semi structured model
 Associative model
 Context model

What is a Relational Database?

Relational model is the most popular and widely used type in DBMS data models. It is more scientific than other data models in DBMS. In a relational models, data is in two-dimensional tables and the relationship is maintained by storing a common field. This is based on first-order predicate logic and defines a table as an n-ary relation.

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