Code360 powered by Coding Ninjas X Naukri.com. Code360 powered by Coding Ninjas X Naukri.com
Table of contents
1.
Example of Entity in DBMS
2.
Types of Entity in DBMS
2.1.
1. Tangible Entity
2.2.
2. Intangible Entity
3.
What is Entity Type in DBMS?
4.
Types Of Entity Type In DBMS
4.1.
1. Strong Entity
4.2.
2. Weak Entity
5.
What is an Entity Set?
6.
Properties Of Entity in DBMS
7.
Difference between an Entity and an Entity Set
8.
Frequently Asked Questions
8.1.
Why are entities important in DBMS?
8.2.
What is difference between entity and attribute?
8.3.
What is Entity Set Representation in DBMS?
8.4.
How Many Entities are There in DBMS?
8.5.
What is Entity Type and Relationship Type?
9.
Conclusion
Last Updated: Jul 15, 2024
Easy

Entity in DBMS

Leveraging ChatGPT - GenAI as a Microsoft Data Expert
Speaker
Prerita Agarwal
Data Specialist @
23 Jul, 2024 @ 01:30 PM

Entity in DBMS refers to a piece of data stored within the database. An entity can represent any person, place, thing, or event that needs to be stored within the database. DBMS are categorized into two types: strong and weak. A database can help keep track of everything and ensure the details are accurate by categorizing the information into tables. An entity is a real-world thing or idea that can be separated from other objects or concepts in DBMS. It is a thing or idea with an exclusive identity and existing independently. An entity in a database is comparable to a thing, such as a person, place, or book. For example, the customer is an entity in a database for a retail store.

entity in dbms

An attribute of an entity is a quality that characterizes it. Name, address, email, or phone number are the entity's attributes in the above example. We store these attributes in columns in the customer table, with each row representing a different customer and containing their specific values for each attribute.

Example of Entity in DBMS

Here's an example of creating and inserting data into the coders1 table for four attributes:

Code

Creating a table named as coders1. Below is the code for table creation. 

CREATE TABLE coders1 (
    coder_id INT PRIMARY KEY,
    first_name VARCHAR(50),
    last_name VARCHAR(50),
    programming_lang VARCHAR(50)
);


Insertion in the table coders1 is given below: 

INSERT INTO coders1 (coder_id, first_name, last_name, programming_lang)

VALUES 
    (1, 'John', 'Doe', 'Java'),
    (2, 'Jane', 'Doe', 'Python'),
    (3, 'Bob', 'Smith', 'C#');


 To get the complete details of the table coders1, we have the below syntax: 

SELECT * FROM coders1;

 

Output

coder_idfirst_namelast_nameprogramming_lang
1JohnDoeJava
2JaneDoePython
3BobSmithC#

In the SQL table example, the entity is coders. In this case, coders represent a group of individuals who work as programmers, and we are storing information about their attributes such as their coder_id, first_name, last_name, and programming_lang.

Types of Entity in DBMS

In this section, we will discuss the categories of entities in DBMS. There are mainly two types (Tangible and Intangible Entities) in DBMS on which we can categorize them. 

  • Tangible Entity
  • Intangible Entity

Here is an explanation of both of them:

1. Tangible Entity

A tangible Entity is one of the entities that are present in the real world physically. In simpler words, you can say the things we can touch and feel are tangible entities such as Persons, Dogs, Products, etc. 

Here is an example of a DBMS table showing the tangible entity:

NameAgeGenderAddress
Kevin25MaleDelhi
Sarah29FemaleMumbai
Bryan36MaleDelhi

In the above table, the entities are the people who have some properties that are name, age, gender, and address. Here the people are the tangible entities that exist in the real world.

2. Intangible Entity

An intangible Entity is an entity where the entity does not exist in the real world but only exists logically. A bank Account, Train Reservation, and Library Account are some of examples of intangible entities. 

Here is an example of a DBMS table showing the intangible entity:

Account NumberHolder NameGender
9740127419KevinMale
0150172793SarahFemale
4180733750BryanMale

In the above table, the entities are the bank accounts which does not exist in real life, as we can not touch or feel them. Here the bank account entity has the properties that are account number, holder name, and gender.

Get the tech career you deserve, faster!
Connect with our expert counsellors to understand how to hack your way to success
User rating 4.7/5
1:1 doubt support
95% placement record
Akash Pal
Senior Software Engineer
326% Hike After Job Bootcamp
Himanshu Gusain
Programmer Analyst
32 LPA After Job Bootcamp
After Job
Bootcamp

What is Entity Type in DBMS?

Have you ever played a game where you had to create characters? For example, in a role-playing game, you might create a character that is a human fighter. This character would have certain attributes, such as strength, dexterity, and intelligence.

Entity types in a DBMS are similar to the character types in a game. An entity type is a category of things that have the same attributes. For example, the entity type "customer" might have the attributes "name," "address," and "phone number."

Every customer in a database would be an instance of the customer entity type. Each customer would have their own unique values for the attributes "name," "address," and "phone number."

Entity types are used to organize data in a database. By using entity types, database designers can create databases that are easier to use and maintain.

Types Of Entity Type In DBMS

There are different types of entity type in DBMS, including:

1. Strong Entity

A strong entity is similar to a person or object that can stand alone and has a distinct identity. 
Let's consider the example of a job interview preparation system that stores information about interview topics and the skills needed for each subject. In this case, topics can be considered strong entities because they exist independently and have a unique identity.

Code: Creating a table named topics. Below is the code for table creation. 

CREATE TABLE topics (
  topic_id INT PRIMARY KEY,
  topic_name VARCHAR(50),
  topic_description TEXT
);


Insertion in the table topics is given below: 

INSERT INTO topics (topic_id, topic_name, topic_description) VALUES
  	(1, 'Data Structures and Algorithms', 'DSA includes fundamental concepts of computer science.'),
  	(2, 'Database Management Systems', 'DBMS allows users to create, update, and manage databases.'),
  	(3, 'Object-Oriented Programming', 'OOPS focuses on objects and their interactions.'),
  	(4, 'Operating Systems', 'Operating systems manage computer hardware and software resources.'),
  	(5, 'Networking', 'Networking involves the design, construction, and use of networks.');


To get the complete details of the table topics, we have the below syntax: 

SELECT * FROM topics;


Output

topic_idtopic_nametopic_description
1Data structures and algorithmsDSA includes fundamental concepts of computer science.
2Database management systemsDBMS allows users to create, update, and manage databases.
3Object-oriented programmingOOPs focus on objects and their interactions.
Operating systemsOperating systems manage computer hardware and software resources.
5NetworkingNetworking involves the design, construction, and use of networks.

2. Weak Entity

A weak entity depends on another entity for identity and cannot function alone. It's like a supporting character needing a significant character to give it purpose.

Here is an example of a weak entity in a database for students studying DSA (Data Structures and Algorithms):

Let's assume we have two tables: Student and Enrollment. Because it cannot exist in this situation without a corresponding Student record, enrollment is a weak entity. Each enrollment needs to be linked to a particular student.

Code

Creating a table named Student and Enrollment. Below is the code for table creation. 

CREATE TABLE Student (
  student_id INT PRIMARY KEY,
  name VARCHAR(50),
  email VARCHAR(50),
  phone VARCHAR(20)
);


Creating Enrollment table. 

CREATE TABLE Enrollment (
  enrollment_id INT PRIMARY KEY,
  student_id INT,
  course_name VARCHAR(50),
  course_start_date DATE,
  course_end_date DATE,
  FOREIGN KEY (student_id) REFERENCES Student(student_id)
);


Insertion in the table Student is given below: 

INSERT INTO Student VALUES
	(1, 'NINJA1', 'ninja1@email.com', '555-1234'),
	(2, 'NINJA2', 'ninja2@email.com', '555-5678');


Insertion in the table Enrollment is given below: 

INSERT INTO Enrollment VALUES
	(1, 1, 'Data Structures', '2022-01-01', '2022-03-15'),
	(2, 1, 'Algorithms', '2022-03-16', '2022-05-31'),
	(3, 2, 'Data Structures', '2022-02-01', '2022-04-15');

 

To get the complete details of the table, Student, we have the below syntax: 

SELECT * FROM Student;


To get the complete details of the table Enrollment, we have the below syntax: 

SELECT * FROM Enrollment;

 

Output

Table 1: Student

student_idnameemailphone
1NINJA1ninja1@email.com555-1234
2NINJA2ninja2@email.com555-5678

 

Table 2: Enrollment

enrollment_idstudent_idcourse_namecourse_start_datecourse_end_date
11Data Structures2022-01-012022-03-15
21Algorithms2022-03-162022-05-31
32Data structures2022-02-012022-04-15

What is an Entity Set?

An entity set resembles a collection of related objects. It is a collection of entities having similar properties and connections to other entities in the database.

For example, we have an entity set named "Programming Languages" in the domain of coding languages, which could include each programming language as a single entity. The same properties, including name, release date, and others, would apply to each programming language in this entity collection. Therefore, things like "Java," "Python," "JavaScript," etc., might all be a part of the "Programming Languages" entity collection.

Properties Of Entity in DBMS

Entities in a database management system (DBMS) have several properties, including:

  1. Name: Each entity has a unique name that identifies it within the database, just like every person has a name that distinguishes them from others
     
  2. Attributes: Attributes are the specific details that belong to an entity. It's similar to how an entity is defined by its traits or characteristics
     
  3. Identity: It functions as a unique identifier that aids in separating one entity from another. It resembles a unique code or number allocated to each entity and can only be used by that entity
     
  4. Constraints: They act as guidelines that limit the kind of data that may be stored in an object. It resembles a collection of requirements that must be satisfied for the data to be acceptable to the entity
     
  5. Relationships: They act as linkages or connections between various database elements. It's similar to connecting two entities based on a shared quality or attribute
     

Here is an example of how the features of entities in DBMS can apply to a coding platform like Coding Ninjas:

  • Name: In Coding Ninjas, an entity's name may be "Course", "Student", or "Mentor"
     
  • Attributes: An entity like "Course" in Coding Ninjas might include characteristics like "Course Name", "Course ID", "Course Length", "Course Cost", "Course Description", and "Course Category"
     
  • Identity: In Coding Ninjas, each "Course" entity will have a unique "Course ID" that sets it apart from other courses. Similarly, every "Student" object will have a unique "Student ID"
     
  • Constraints: Coding Ninjas could have limitations on the "Course" entity such as "Minimum Age Limit", "Pre-requisites", and "Maximum Capacity"
     
  • Relationships: An entity like "Course" in Coding Ninjas might have relationships with other entities such as "Student", "Mentor", or "Course Material". For example, each "Course" entity may be linked to several "Student" entities registered for the course

Difference between an Entity and an Entity Set

FeatureEntityEntity Set
DefinitionAn individual object with a distinct identity that can be distinctly identified in the real world.A collection or group of similar entities.
CardinalityRepresents a single occurrence of an object.Encompasses multiple occurrences of entities.
ExampleAn employee with a specific employee ID.A set of all employees working in a company.
UniquenessEach entity must have a unique identity.Different entities within the set must have distinct identities.
InstanceOne specific occurrence of an entity.Multiple instances make up the entity set.

Frequently Asked Questions

Why are entities important in DBMS?

Entities are crucial in DBMS as they represent real-world objects, such as customers, products, or orders, and their attributes. They serve as the foundation for designing databases, enabling structured storage, retrieval, and manipulation of data, ensuring data integrity and consistency.

What is difference between entity and attribute?

Entities are objects or concepts in a database, such as customers or products, while attributes are the properties or characteristics of these entities, such as customer name or product price. Entities represent the "what" of the data, while attributes represent the "details" or "qualities" of the entities.

What is Entity Set Representation in DBMS?

In DBMS, an entity set representation refers to a collection of similar entities within a database, depicted as a table where each row represents a unique entity and each column represents its attributes.

How Many Entities are There in DBMS?

The number of entities in a DBMS depends on the specific application and database design. It can range from a few to several thousand, each representing distinct real-world objects or concepts.

What is Entity Type and Relationship Type?

An entity type defines a collection of similar entities with common attributes in a database. A relationship type describes the associations between entity types, specifying how entities from different sets are related to each other.

Conclusion

In conclusion, entities are fundamental building blocks of a database management system. Entities in DBMS have been extensively discussed in this article. We've discussed what entities are, their characteristics, and their attributes. We have included various examples, including coding platforms and programming languages, to simplify them.

You may better grasp the topics of DBMS by reading some articles below that go into further detail and give examples.

Live masterclass