In this article Relational Model in DBMS we give the information about The Relational Model is a theoretical framework for managing data using the concept of relations (tables). Proposed by E.F. Codd in 1970, it forms the basis for relational database systems.
Introduction to the Relational Model:
What is the Relational Model?
The Relational Model is a theoretical framework for managing data using the concept of relations (tables). Proposed by E.F. Codd in 1970, it forms the basis for relational database systems.
- Data is represented in tables (relations).
- Each table consists of rows (tuples) and columns (attributes).
- The relational model provides simplicity, flexibility, and data independence.
Core Concepts of the Relational Model:
| Term | Description | Example |
| Relation | A table with rows and columns | Student table |
| Tuple | A single row in a table | (101, “Ravi”, “BCA”) |
| Attribute | A column in a table | RollNo, Name, Course |
| Domain | The set of valid values for an attribute | Age domain: 0 to 150 |
| Degree | Number of attributes (columns) in a relation | 3 for Student(RollNo, Name, Course) |
| Cardinality | Number of tuples (rows) in a relation | 50 students in Student table |
| Primary Key | Unique identifier for a tuple | RollNo in the Student table |
| Foreign Key | Attribute that refers to a primary key in another relation | CourseID in Enrollment table |
Example: Student Table (Relation)
| RollNo | Name | Course |
| 101 | Ravi | BCA |
| 102 | Meena | MCA |
- Relation name: Student
- Attributes: RollNo, Name, Course
- Tuples: (101, Ravi, BCA), (102, Meena, MCA)
- Primary Key: RollNo
Relational Schema
What is a Relational Schema?
A relational schema defines the structure of a relation (table). It includes:
- The name of the relation
- The name and data type of each attribute
- Any constraints (e.g., primary key, foreign key)
Notation:
Student(RollNo: INT, Name: VARCHAR, Course: VARCHAR)
Features of a Relational Schema:
- Acts as a blueprint for a relation
Example:
- Schema:
- Specifies attribute names and their domains
- Includes keys and integrity constraints
Student(RollNo INT PRIMARY KEY, Name VARCHAR(50), Course VARCHAR(30))
Description:
- Relation: Student
- Attributes: RollNo, Name, Course
- Constraint: RollNo is the primary key
Advantages of Relational Model
| Advantage | Explanation |
| Simplicity | Data is organized in easily understandable tabular format |
| Data Independence | Logical and physical data are separated |
| Flexibility | Easy to add or remove attributes and tuples |
| Integrity | Enforces constraints like primary keys, foreign keys, etc. |
| Query Capability | Supports SQL for powerful and flexible data retrieval |
Disadvantages
| Disadvantage | Explanation |
| Performance Issues | May be slower with very large datasets or complex queries |
| Not Ideal for Complex Data | Less suitable for multimedia, semi-structured or nested data |
Conclusion
The Relational Model and its structure, the Relational Schema, provide a robust, efficient, and logical way to organize and manage data in a database. They form the core of modern relational database systems, offering both theoretical foundation and practical implementation for data storage and retrieval.
POP- Introduction to Programming Using ‘C’
OOP – Object Oriented Programming
DBMS – Database Management System
RDBMS – Relational Database Management System
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