Question

What do you mean by relational database? Give its one example.

Hint:

Relational databases use keys to establish relationships: Primary Keys uniquely identify records in a table, while Foreign Keys link to Primary Keys in other tables, creating referential integrity.

Answer 1

Definition of Relational Database:  

A relational database is a type of database that stores and organizes data in tables (also called relations) consisting of rows and columns. It establishes relationships between different tables using common fields. 

The concept of relational database was introduced by E. F. Codd in 1970. 

Key Characteristics:

• Tables: Data is stored in tables representing entities (e.g., Students, Employees, Products).
• Rows (Records/Tuples): Each row represents a single record.
• Columns (Fields/Attributes): Each column represents an attribute of the entity.
• Primary Key: A unique identifier for each row.
• Foreign Key: A field that links one table to another.
• Relationships: One-to-one, One-to-many, Many-to-many.
• SQL (Structured Query Language): Used to query and manage data.

Advantages of Relational Databases:

• Data integrity and accuracy
• Reduced redundancy
• Easy data retrieval using SQL
• Flexible querying
• Data security
• Support for complex relationships

Example: School Management System 

Table 1: Students 

 

StudentID (Primary Key)	Name	Age	Grade
101	Alice Johnson	15	10
102	Bob Smith	16	11
103	Charlie Brown	15	10
104	Diana Prince	17	12

Table 2: Courses 

 

CourseID (Primary Key)	CourseName	Credits
CS101	Computer Science	3
MATH201	Mathematics	4
ENG102	English Literature	2
SCI103	Science	3

Table 3: Enrollments (Relationship Table) 

 

EnrollmentID	StudentID (Foreign Key)	CourseID (Foreign Key)
1	101	CS101
2	101	MATH201
3	102	ENG102
4	103	CS101
5	104	SCI103
6	104	MATH201

How It Works:

• The Students table stores student details.
• The Courses table stores course information.
• The Enrollments table links students and courses.
• StudentID in Enrollments references Students table.
• CourseID in Enrollments references Courses table.

This structure allows queries such as:

• Which courses is Alice Johnson enrolled in?
• How many students are taking Computer Science?
• Which students are in Grade 10?

Common Relational Database Management Systems (RDBMS):

• MySQL
• PostgreSQL
• Oracle Database
• Microsoft SQL Server
• SQLite
• MariaDB

Final Answer: 

A relational database organizes data into tables with rows and columns and establishes relationships between them using keys. Example: Students, Courses, and Enrollments tables in a school database.