SQL is a standard language used to manage and manipulate relational databases.

A Join is used to combine records from multiple tables using a common attribute.

IT405 Unit 2 DBMS Notes | Relational Model, SQL, Relational Algebra

Q: What is Relational Model?

Relational Model is a database model where data is stored in tables called relations.

Q: What is Relational Algebra?

Relational Algebra is a procedural query language used for database operations.

Q: What is Referential Integrity?

Referential Integrity ensures that Foreign Key values always reference valid Primary Key values.

What You Will Learn in DBMS Unit 2?

DBMS Unit 2 is one of the most practical and scoring units in the Database Management System syllabus. In this unit, students learn how data is stored inside tables and how SQL is used to retrieve, insert, update and delete data.

This unit forms the foundation of database programming, web development, backend development and software engineering. Almost every company uses SQL databases, making this unit extremely important for both examinations and placements.

UNIT 2 ROADMAP ↓ Relational Model ↓ Relational Algebra ↓ Relational Calculus ↓ SQL ↓ DDL ↓ DML ↓ DCL ↓ TCL ↓ Joins ↓ Views ↓ Integrity Constraints

What You Will Learn in DBMS Unit 2?

DBMS Unit 2 is one of the most practical and scoring units in the Database Management System syllabus. In this unit, students learn how data is stored inside tables and how SQL is used to retrieve, insert, update and delete data.

This unit forms the foundation of database programming, web development, backend development and software engineering. Almost every company uses SQL databases, making this unit extremely important for both examinations and placements.

UNIT 2 ROADMAP ↓ Relational Model ↓ Relational Algebra ↓ Relational Calculus ↓ SQL ↓ DDL ↓ DML ↓ DCL ↓ TCL ↓ Joins ↓ Views ↓ Integrity Constraints

Relational Algebra

Relational Algebra DBMS ka procedural query language hai. Iska use relational databases par operations perform karne ke liye kiya jata hai.

Relational Algebra SQL ka foundation mana jata hai. SQL ke bahut saare commands Relational Algebra operations par based hote hain.

Definition

Relational Algebra is a procedural query language that uses various operations to retrieve and manipulate data from relational databases.

Why Relational Algebra is Important?

SQL ka base concept hai.
Data retrieval operations ko define karta hai.
Query processing ko simplify karta hai.
Database operations ko mathematically represent karta hai.

Basic Concept

Table ↓ Relational Algebra Operation ↓ Result Table

Input bhi relation hota hai aur output bhi relation hota hai.

Types of Operations

Relational Algebra │ ├── Selection (σ) ├── Projection (π) ├── Union (∪) ├── Set Difference (-) ├── Intersection (∩) ├── Cartesian Product (×) ├── Join (⨝) └── Division (÷)

Student Relation Example

Roll No	Name	Branch	Marks
101	Shivam	CSE	85
102	Rahul	IT	78
103	Aman	CSE	90

1. Selection Operation (σ)

Selection operation rows ko select karta hai based on a condition.

Symbol

σ

Example

σ Branch='CSE' (Student)

Ye query sirf CSE students ko return karegi.

2. Projection Operation (π)

Projection operation selected columns ko display karta hai.

Symbol

π

Example

π Name, Branch (Student)

Sirf Name aur Branch columns display honge.

3. Union Operation (∪)

Union do relations ke tuples ko combine karta hai.

Example

Student_CSE ∪ Student_IT

Result me dono tables ke records aa jayenge.

Conditions for Union

Same number of attributes
Same data type
Compatible relations

4. Set Difference Operation (-)

Set Difference ek relation ke tuples ko return karta hai jo doosre relation me present nahi hote.

Example

Student - Passed_Students

Result me failed students milenge.

5. Intersection Operation (∩)

Intersection common tuples return karta hai.

Example

A ∩ B

Result me sirf common records aayenge.

6. Cartesian Product (×)

Cartesian Product do relations ke sabhi possible combinations generate karta hai.

Example

Student × Course

Formula

If Relation A has m rows and Relation B has n rows:

Result Rows = m × n

7. Join Operation (⨝)

Join operation do tables ko common attribute ke basis par combine karta hai.

Example

Student ⨝ Department

Student aur Department tables merge ho jayengi.

Types of Join

Inner Join
Outer Join
Left Join
Right Join
Natural Join

8. Division Operation (÷)

Division operation advanced queries ke liye use hota hai.

Ye generally "for all" type questions solve karne me use hota hai.

Example of Division

Find students who have completed all courses.

Student_Course ÷ Courses

Advantages of Relational Algebra

Simple mathematical foundation.
SQL ka base provide karta hai.
Query optimization me useful.
Easy data retrieval.
Powerful database operations.

Disadvantages of Relational Algebra

Direct end-user use nahi karte.
Complex queries difficult ho sakti hain.
Procedural nature.

Summary Table

Operation	Symbol	Purpose
Selection	σ	Select Rows
Projection	π	Select Columns
Union	∪	Combine Tuples
Difference	-	Remove Common Tuples
Intersection	∩	Common Tuples
Cartesian Product	×	All Combinations
Join	⨝	Combine Tables
Division	÷	Advanced Queries

Memory Trick

σ ↓ Rows ---------------- π ↓ Columns ---------------- ∪ ↓ Combine ---------------- ∩ ↓ Common ---------------- ⨝ ↓ Join Tables

RGPV Exam Keywords

Relational Algebra
Selection
Projection
Union
Intersection
Difference
Cartesian Product
Join
Division
Procedural Query Language

Most Expected Questions

2 Marks

Define Relational Algebra.
What is Selection?
What is Projection?
What is Join?

5 Marks

Explain Selection and Projection.
Explain Cartesian Product.
Explain Join Operation.

7 Marks

Explain basic operations of Relational Algebra.
Explain Join and Division operations.
Discuss Relational Algebra with examples.

14 Marks

Explain Relational Algebra in detail. Discuss Selection, Projection, Union, Difference, Intersection, Cartesian Product, Join and Division operations with examples.

Relational Calculus

Relational Calculus DBMS ka non-procedural query language hai. Relational Algebra me hume batana padta hai ki result kaise obtain karna hai, jabki Relational Calculus me sirf ye batana hota hai ki hume kya result chahiye.

Relational Calculus mathematical predicate logic par based hota hai aur SQL ke development me iska important contribution raha hai.

Definition

Relational Calculus is a non-procedural query language that specifies what data is required without specifying how to retrieve it.

Basic Concept

Relational Algebra ↓ How to Retrieve Data ------------------------ Relational Calculus ↓ What Data is Required

Procedural vs Non-Procedural Language

Procedural Language	Non-Procedural Language
Specifies HOW	Specifies WHAT
Relational Algebra	Relational Calculus
Step-by-Step Operations	Desired Result Only
More Complex	Easier to Write

Types of Relational Calculus

Relational Calculus │ ├── Tuple Relational Calculus (TRC) └── Domain Relational Calculus (DRC)

1. Tuple Relational Calculus (TRC)

Tuple Relational Calculus me variables tuples ko represent karte hain.

Query tuple variables ki help se likhi jati hai.

General Form

{ t | P(t) }

Where:

t = Tuple Variable
P(t) = Predicate Condition

Example

Find all students having marks greater than 80.

{ t | Student(t) AND t.Marks > 80 }

Student Relation

Roll No	Name	Marks
101	Shivam	85
102	Rahul	70
103	Aman	90

Result:

Shivam Aman

Advantages of TRC

Simple query representation.
Focus on desired result.
No need to specify retrieval procedure.

2. Domain Relational Calculus (DRC)

Domain Relational Calculus me variables attribute values ko represent karte hain.

Tuple ki jagah individual attribute values use ki jati hain.

General Form

{ | P(x1,x2,x3...) }

Example

Find names of students having marks greater than 80.

{ | Student(RollNo, Name, Marks) AND Marks > 80 }

TRC vs DRC

TRC	DRC
Uses Tuple Variables	Uses Domain Variables
Tuple Based	Attribute Based
Easier Representation	Detailed Representation
Entire Tuple Considered	Individual Attributes Considered

Free Variables

Free Variable wo variable hota hai jo query result me appear karta hai.

Ye result generate karne ke liye use hota hai.

Bound Variables

Bound Variable logical quantifiers ke under define kiya jata hai.

Ye query evaluation ke liye use hota hai.

Quantifiers in Relational Calculus

Quantifiers │ ├── Universal Quantifier (∀) └── Existential Quantifier (∃)

Universal Quantifier (∀)

Universal Quantifier ka meaning hota hai "For All".

Example:

All students passed the exam.

∀ Student

Existential Quantifier (∃)

Existential Quantifier ka meaning hota hai "There Exists".

Example:

There exists a student whose marks are greater than 90.

∃ Student

Advantages of Relational Calculus

Easy query formulation.
Non-procedural approach.
User friendly.
Mathematical foundation.
Flexible query specification.

Disadvantages of Relational Calculus

Complex syntax.
Not directly used by end users.
Difficult for beginners.

Relational Algebra vs Relational Calculus

Relational Algebra	Relational Calculus
Procedural	Non-Procedural
Specifies HOW	Specifies WHAT
Operation Based	Predicate Logic Based
More Detailed	More Abstract
Uses Operators	Uses Quantifiers

Memory Trick

TRC ↓ Tuple ------------------- DRC ↓ Domain ------------------- Algebra ↓ HOW ------------------- Calculus ↓ WHAT

RGPV Exam Keywords

Relational Calculus
Tuple Relational Calculus
Domain Relational Calculus
TRC
DRC
Free Variable
Bound Variable
Universal Quantifier
Existential Quantifier
Non-Procedural Query Language

Most Expected Questions

2 Marks

Define Relational Calculus.
What is TRC?
What is DRC?
What is a Quantifier?

5 Marks

Explain Tuple Relational Calculus.
Explain Domain Relational Calculus.
Differentiate TRC and DRC.

7 Marks

Explain Relational Calculus with examples.
Differentiate Relational Algebra and Relational Calculus.
Explain quantifiers used in Relational Calculus.

14 Marks

Explain Relational Calculus in detail. Discuss Tuple Relational Calculus, Domain Relational Calculus, Quantifiers and comparison with Relational Algebra.

Introduction to SQL

SQL (Structured Query Language) DBMS ki sabse important language hai. SQL ka use database ko create, manage, modify aur retrieve karne ke liye kiya jata hai.

Aaj ke modern databases jaise MySQL, Oracle, PostgreSQL, MariaDB aur SQL Server sab SQL support karte hain.

RGPV exams me SQL se direct 7 marks aur 14 marks ke questions frequently pooche jate hain.

Definition

SQL (Structured Query Language) is a standard database language used to create, retrieve, update and manage data in relational databases.

Why SQL is Needed?

Database create karne ke liye.
Data insert karne ke liye.
Data retrieve karne ke liye.
Data update karne ke liye.
Data delete karne ke liye.
User permissions manage karne ke liye.

Basic Concept of SQL

User ↓ SQL Query ↓ DBMS ↓ Database ↓ Result

History of SQL

SQL IBM ke researchers ne develop ki thi.

Ye Relational Model ke creator Dr. E. F. Codd ke concepts par based hai.

SQL ko ANSI aur ISO standards ne adopt kiya hai.

Features of SQL

Easy to learn.
Standard language.
Portable.
Supports complex queries.
High performance.
Database independent.
Supports security.
Supports transactions.

Applications of SQL

Banking Systems
College Management Systems
Hospital Databases
E-Commerce Websites
Railway Reservation Systems
Social Media Platforms

Components of SQL

SQL │ ├── DDL ├── DML ├── DCL └── TCL

1. DDL (Data Definition Language)

DDL database structure define karne ke liye use hoti hai.

Commands:

CREATE
ALTER
DROP
TRUNCATE

2. DML (Data Manipulation Language)

DML data insert, update aur delete karne ke liye use hoti hai.

Commands:

INSERT
UPDATE
DELETE
SELECT

3. DCL (Data Control Language)

DCL database security aur permissions manage karti hai.

Commands:

GRANT
REVOKE

4. TCL (Transaction Control Language)

TCL transactions ko manage karti hai.

Commands:

COMMIT
ROLLBACK
SAVEPOINT

SQL Architecture

Application ↓ SQL Query ↓ DBMS Engine ↓ Database

Example Database

Roll_No	Name	Branch	Marks
101	Shivam	CSE	85
102	Rahul	IT	78

Example SQL Query

SELECT * FROM Student;

Ye query Student table ke sabhi records display karegi.

SQL Processing Steps

Write Query ↓ Parse Query ↓ Optimize Query ↓ Execute Query ↓ Display Result

Advantages of SQL

Simple syntax.
Fast data retrieval.
Standard language.
Supports security.
Supports large databases.
Easy maintenance.
Supports transactions.

Disadvantages of SQL

Complex queries difficult ho sakti hain.
Vendor-specific extensions exist karte hain.
Very large systems me optimization required hoti hai.

Real Life Example

Suppose College Database me 5000 students hain.

Agar hume CSE students ki list chahiye to SQL query use kar sakte hain:

SELECT * FROM Student WHERE Branch='CSE';

Ye query sirf CSE students display karegi.

SQL vs Relational Algebra

SQL	Relational Algebra
Practical Language	Theoretical Language
Used by Developers	Used for Concepts
User Friendly	Mathematical
Industry Standard	Foundation of SQL

Memory Trick

SQL ↓ Create Store Retrieve Update Delete

Exam Shortcut

DDL ↓ Structure ---------------- DML ↓ Data ---------------- DCL ↓ Security ---------------- TCL ↓ Transactions

RGPV Exam Keywords

Structured Query Language
SQL
DDL
DML
DCL
TCL
Database Query
Transaction
Security
Relational Database

Most Expected Questions

2 Marks

What is SQL?
Define DDL.
Define DML.
What is DCL?

5 Marks

Explain SQL features.
Explain SQL architecture.
Write applications of SQL.

7 Marks

Explain SQL and its components.
Discuss advantages of SQL.
Differentiate SQL and Relational Algebra.

14 Marks

Explain SQL in detail. Discuss its features, architecture, components, applications, advantages and disadvantages.

DDL Commands (Data Definition Language)

DDL (Data Definition Language) SQL ka wo part hai jo database ki structure ko define aur modify karne ke liye use hota hai.

DDL commands tables, databases aur schemas ko create, alter aur delete karne ke liye use ki jati hain.

Definition

DDL (Data Definition Language) is a set of SQL commands used to define, modify and manage database structures.

Purpose of DDL

Database create karna
Table create karna
Table structure modify karna
Table delete karna
Database objects manage karna

DDL Commands List

DDL Commands │ ├── CREATE ├── ALTER ├── DROP └── TRUNCATE

1. CREATE Command

CREATE command ka use database ya table create karne ke liye hota hai.

Syntax

CREATE TABLE Student ( Roll_No INT, Name VARCHAR(50), Branch VARCHAR(20), Marks INT );

Example

CREATE TABLE Student ( Roll_No INT PRIMARY KEY, Name VARCHAR(50), Branch VARCHAR(20) );

Result

Roll_No	Name	Branch

Student table successfully create ho jayegi.

2. ALTER Command

ALTER command existing table ki structure ko modify karne ke liye use hoti hai.

Add Column

ALTER TABLE Student ADD Marks INT;

Result

Roll_No	Name	Branch	Marks

Modify Column

ALTER TABLE Student MODIFY Name VARCHAR(100);

Drop Column

ALTER TABLE Student DROP COLUMN Marks;

3. DROP Command

DROP command database object ko permanently delete kar deta hai.

Delete hone ke baad data recover nahi hota.

Syntax

DROP TABLE Student;

Effect

Table Structure ❌ Deleted ------------------- Data ❌ Deleted

4. TRUNCATE Command

TRUNCATE command table ke saare records remove kar deta hai lekin table structure ko preserve rakhta hai.

Syntax

TRUNCATE TABLE Student;

Before TRUNCATE

Roll No	Name
101	Shivam
102	Rahul

After TRUNCATE

Roll No	Name

Table empty ho jayegi lekin structure exist karega.

CREATE vs ALTER vs DROP vs TRUNCATE

Command	Purpose
CREATE	Create New Table
ALTER	Modify Table Structure
DROP	Delete Table + Structure
TRUNCATE	Delete Data Only

DROP vs TRUNCATE

DROP	TRUNCATE
Deletes Structure	Keeps Structure
Deletes Data	Deletes Data
Cannot Reuse Table	Can Reuse Table
Permanent Removal	Only Records Removed

Real Life Example

Suppose College Database me Student table create karni hai:

CREATE TABLE Student ↓ ADD Marks ↓ MODIFY Name ↓ TRUNCATE Records ↓ DROP Table

Advantages of DDL

Easy database creation.
Easy structure modification.
Fast table management.
Supports database design.
Reduces development effort.

Memory Trick

CREATE ↓ Create Table ------------------- ALTER ↓ Change Table ------------------- DROP ↓ Delete Table ------------------- TRUNCATE ↓ Delete Data

Exam Shortcut

Command	Remember
CREATE	New Table
ALTER	Modify Structure
DROP	Remove Table
TRUNCATE	Remove Records

RGPV Exam Keywords

DDL
CREATE
ALTER
DROP
TRUNCATE
Database Structure
Table Creation
Schema Modification
Permanent Deletion

Most Expected Questions

2 Marks

Define DDL.
What is CREATE command?
What is ALTER command?
What is TRUNCATE command?

5 Marks

Explain CREATE command with example.
Explain ALTER command with example.
Differentiate DROP and TRUNCATE.

7 Marks

Explain DDL commands with syntax and examples.
Discuss CREATE, ALTER, DROP and TRUNCATE commands.
Differentiate all DDL commands.

14 Marks

Explain DDL (Data Definition Language) in detail. Discuss CREATE, ALTER, DROP and TRUNCATE commands with syntax, examples and comparison.

DML Commands (Data Manipulation Language)

DML (Data Manipulation Language) SQL ka important part hai jo database ke andar stored data ko manipulate karne ke liye use hota hai.

DDL database structure ko manage karti hai, jabki DML actual records par operations perform karti hai.

Definition

DML (Data Manipulation Language) is a set of SQL commands used to insert, retrieve, update and delete data from database tables.

Purpose of DML

New records insert karna
Existing records retrieve karna
Records update karna
Records delete karna
Database data manage karna

DML Commands

DML Commands │ ├── INSERT ├── SELECT ├── UPDATE └── DELETE

Student Table Example

Roll_No	Name	Branch	Marks

1. INSERT Command

INSERT command table me new records add karne ke liye use hoti hai.

Syntax

INSERT INTO Student VALUES (101,'Shivam','CSE',85);

Example

INSERT INTO Student VALUES (102,'Rahul','IT',78);

Result

Roll_No	Name	Branch	Marks
101	Shivam	CSE	85
102	Rahul	IT	78

2. SELECT Command

SELECT command database se data retrieve karne ke liye use hoti hai.

Ye SQL ki sabse frequently used command hai.

Syntax

SELECT * FROM Student;

Result

Student table ke sabhi records display honge.

Specific Columns Select Karna

SELECT Name, Marks FROM Student;

WHERE Clause

WHERE clause specific condition apply karne ke liye use hota hai.

Example

SELECT * FROM Student WHERE Branch='CSE';

Result

Sirf CSE students display honge.

Comparison Operators

Operator	Meaning
=	Equal To
>	Greater Than
<	Less Than
>=	Greater Than Equal
<=	Less Than Equal
!=	Not Equal

Example Queries

SELECT * FROM Student WHERE Marks > 80;

SELECT Name FROM Student WHERE Branch='IT';

3. UPDATE Command

UPDATE command existing records ko modify karne ke liye use hoti hai.

Syntax

UPDATE Student SET Marks = 90 WHERE Roll_No = 101;

Before Update

Roll_No	Name	Marks
101	Shivam	85

After Update

Roll_No	Name	Marks
101	Shivam	90

4. DELETE Command

DELETE command table se records remove karne ke liye use hoti hai.

Syntax

DELETE FROM Student WHERE Roll_No = 102;

Result

Roll Number 102 wala record delete ho jayega.

Delete All Records

DELETE FROM Student;

Table ke saare records delete ho jayenge lekin structure rahega.

SELECT vs DELETE vs UPDATE

Command	Purpose
SELECT	Retrieve Data
UPDATE	Modify Data
DELETE	Remove Data

INSERT vs UPDATE

INSERT	UPDATE
Add New Record	Modify Existing Record
Creates New Row	Changes Existing Row

Real Life Example

Admission ↓ INSERT Student ------------------- View Result ↓ SELECT Student ------------------- Correction ↓ UPDATE Student ------------------- Remove Record ↓ DELETE Student

Advantages of DML

Easy data management.
Fast record retrieval.
Supports updates.
Flexible operations.
Efficient database handling.

Memory Trick

INSERT ↓ Add Data ----------------- SELECT ↓ View Data ----------------- UPDATE ↓ Modify Data ----------------- DELETE ↓ Remove Data

Exam Shortcut

Command	Remember
INSERT	Add Record
SELECT	Show Record
UPDATE	Change Record
DELETE	Remove Record

RGPV Exam Keywords

DML
INSERT
SELECT
UPDATE
DELETE
WHERE Clause
Data Retrieval
Data Modification
Database Records

Most Expected Questions

2 Marks

Define DML.
What is INSERT command?
What is UPDATE command?
What is DELETE command?

5 Marks

Explain SELECT command with example.
Explain UPDATE command.
Explain DELETE command.

7 Marks

Explain DML commands with syntax and examples.
Discuss INSERT, SELECT, UPDATE and DELETE commands.
Explain WHERE clause with examples.

14 Marks

Explain DML (Data Manipulation Language) in detail. Discuss INSERT, SELECT, UPDATE and DELETE commands with syntax, examples and comparison.

DCL Commands (Data Control Language)

DCL (Data Control Language) SQL ka wo part hai jo database security aur user permissions ko manage karta hai.

DCL commands determine karti hain ki kaun user database ke kis part ko access kar sakta hai.

Definition

DCL (Data Control Language) is a set of SQL commands used to control access permissions and security in a database.

Why DCL is Needed?

Database security maintain karne ke liye.
Unauthorized access rokne ke liye.
User permissions manage karne ke liye.
Data protection provide karne ke liye.

DCL Commands

DCL │ ├── GRANT └── REVOKE

1. GRANT Command

GRANT command kisi user ko database permissions dene ke liye use hoti hai.

Syntax

GRANT Permission ON Table_Name TO User_Name;

Example

GRANT SELECT ON Student TO Rahul;

Meaning

Rahul user ab Student table ko read kar sakta hai.

Multiple Permissions Example

GRANT SELECT, INSERT, UPDATE ON Student TO Rahul;

2. REVOKE Command

REVOKE command previously granted permissions ko remove karne ke liye use hoti hai.

Syntax

REVOKE Permission ON Table_Name FROM User_Name;

Example

REVOKE SELECT ON Student FROM Rahul;

Meaning

Rahul ab Student table ko access nahi kar sakta.

GRANT vs REVOKE

GRANT	REVOKE
Provides Permission	Removes Permission
Access Allow	Access Deny
Security Setup	Security Removal

Real Life Example

Admin ↓ GRANT Access ↓ Faculty ------------------- Admin ↓ REVOKE Access ↓ Faculty

TCL Commands (Transaction Control Language)

TCL (Transaction Control Language) transactions ko manage karne ke liye use hoti hai.

Transaction ka matlab database operations ka group hota hai jo ek unit ki tarah execute hota hai.

Definition

TCL (Transaction Control Language) is a set of SQL commands used to manage database transactions.

What is a Transaction?

Transaction database operations ka logical unit hota hai.

Example:

Bank Account Transfer

Account A ↓ Withdraw ₹1000 ↓ Account B ↓ Deposit ₹1000

Ye complete process ek transaction hai.

TCL Commands

TCL │ ├── COMMIT ├── ROLLBACK └── SAVEPOINT

1. COMMIT Command

COMMIT command transaction ko permanently save kar deta hai.

Syntax

COMMIT;

Example

UPDATE Student SET Marks = 90 WHERE Roll_No = 101; COMMIT;

Result

Changes permanently database me save ho jayenge.

2. ROLLBACK Command

ROLLBACK command transaction ko undo kar deta hai.

Syntax

ROLLBACK;

Example

UPDATE Student SET Marks = 50 WHERE Roll_No = 101; ROLLBACK;

Result

Database previous state me wapas aa jayega.

3. SAVEPOINT Command

SAVEPOINT transaction ke andar temporary checkpoint create karta hai.

Syntax

SAVEPOINT SP1;

Example

UPDATE Student SET Marks = 90 WHERE Roll_No = 101; SAVEPOINT SP1; UPDATE Student SET Marks = 95 WHERE Roll_No = 101;

Rollback to Savepoint

ROLLBACK TO SP1;

Database SP1 state tak return ho jayega.

Transaction Flow

Start Transaction ↓ Execute Query ↓ SAVEPOINT ↓ More Operations ↓ COMMIT OR ROLLBACK

COMMIT vs ROLLBACK

COMMIT	ROLLBACK
Save Changes	Undo Changes
Permanent	Temporary Undo
Transaction Success	Transaction Failure

Advantages of TCL

Ensures data consistency.
Supports recovery.
Provides transaction control.
Improves reliability.
Protects against failures.

Memory Trick

GRANT ↓ Give Permission ------------------- REVOKE ↓ Remove Permission ------------------- COMMIT ↓ Save Changes ------------------- ROLLBACK ↓ Undo Changes ------------------- SAVEPOINT ↓ Checkpoint

Exam Shortcut

Command	Purpose
GRANT	Allow Access
REVOKE	Remove Access
COMMIT	Save Transaction
ROLLBACK	Undo Transaction
SAVEPOINT	Create Checkpoint

RGPV Exam Keywords

DCL
GRANT
REVOKE
TCL
COMMIT
ROLLBACK
SAVEPOINT
Transaction
Database Security
Access Control

Most Expected Questions

2 Marks

Define DCL.
Define TCL.
What is COMMIT?
What is SAVEPOINT?

5 Marks

Explain GRANT and REVOKE.
Explain COMMIT and ROLLBACK.
Explain SAVEPOINT with example.

7 Marks

Explain DCL commands with syntax and examples.
Explain TCL commands with examples.
Differentiate COMMIT and ROLLBACK.

14 Marks

Explain DCL and TCL commands in detail. Discuss GRANT, REVOKE, COMMIT, ROLLBACK and SAVEPOINT with syntax, examples and comparison.

SQL Joins

SQL Join ka use do ya do se adhik tables ko common field ke basis par connect karne ke liye kiya jata hai.

Real-world databases me data multiple tables me store hota hai. Isliye information retrieve karne ke liye Joins ka use bahut important hota hai.

RGPV exams me SQL Joins se frequently 7 marks aur 14 marks ke questions pooche jate hain.

Definition

A Join is an SQL operation used to combine rows from two or more tables based on a related column between them.

Why Joins are Needed?

Multiple tables se data retrieve karne ke liye.
Data redundancy reduce karne ke liye.
Database normalization support karne ke liye.
Related information combine karne ke liye.

Example Tables

Student Table

Roll_No	Name	Dept_ID
101	Shivam	D1
102	Rahul	D2
103	Aman	D1

Department Table

Dept_ID	Department
D1	CSE
D2	IT

Types of SQL Joins

SQL Joins │ ├── Inner Join ├── Left Join ├── Right Join ├── Full Outer Join ├── Natural Join └── Self Join

1. Inner Join

Inner Join sirf matching records return karta hai.

Syntax

SELECT * FROM Student INNER JOIN Department ON Student.Dept_ID = Department.Dept_ID;

Result

Name	Department
Shivam	CSE
Rahul	IT
Aman	CSE

Inner Join Diagram

Table A ◯◯◉ ◉ = Common Records ◉◯◯ Table B

2. Left Join (Left Outer Join)

Left Join left table ke saare records return karta hai aur matching records right table se lata hai.

Syntax

SELECT * FROM Student LEFT JOIN Department ON Student.Dept_ID = Department.Dept_ID;

Result

Student table ke saare records display honge chahe Department match kare ya nahi.

Left Join Diagram

◉◉◉◉ ◉◉ Left Table Priority

3. Right Join (Right Outer Join)

Right Join right table ke saare records return karta hai aur matching records left table se lata hai.

Syntax

SELECT * FROM Student RIGHT JOIN Department ON Student.Dept_ID = Department.Dept_ID;

Right Join Diagram

◉◉ ◉◉◉◉ Right Table Priority

4. Full Outer Join

Full Outer Join dono tables ke saare records return karta hai.

Matching aur non-matching dono records include hote hain.

Syntax

SELECT * FROM Student FULL OUTER JOIN Department ON Student.Dept_ID = Department.Dept_ID;

Diagram

Entire Table A + Entire Table B

5. Natural Join

Natural Join automatically same name wale columns ke basis par join perform karta hai.

Syntax

SELECT * FROM Student NATURAL JOIN Department;

Advantage

ON condition explicitly likhne ki zarurat nahi hoti.

6. Self Join

Self Join me table khud ke saath join hoti hai.

Example

Employee aur Manager relationship.

Employee ↓ Manager ↓ Employee

Syntax

SELECT E1.Name, E2.Name FROM Employee E1, Employee E2 WHERE E1.Manager_ID = E2.Employee_ID;

Join Operation Working

Table A + Table B ↓ Common Column ↓ Join Condition ↓ Combined Result

Inner Join vs Outer Join

Inner Join	Outer Join
Only Matching Rows	Matching + Non-Matching Rows
Smaller Result	Larger Result
Most Common	Special Cases

Left Join vs Right Join

Left Join	Right Join
All Left Records	All Right Records
Left Table Priority	Right Table Priority

Advantages of Joins

Multiple tables combine kar sakte hain.
Data redundancy reduce hoti hai.
Complex reports generate kar sakte hain.
Normalized databases support karte hain.
Data retrieval efficient hota hai.

Memory Trick

INNER ↓ Only Match ------------------- LEFT ↓ All Left ------------------- RIGHT ↓ All Right ------------------- FULL ↓ All Records ------------------- SELF ↓ Same Table

Exam Shortcut

Join	Remember
Inner Join	Common Records
Left Join	All Left Records
Right Join	All Right Records
Full Join	Everything
Self Join	Same Table

RGPV Exam Keywords

SQL Join
Inner Join
Outer Join
Left Join
Right Join
Natural Join
Self Join
Join Condition
Foreign Key
Common Attribute

Most Expected Questions

2 Marks

Define Join.
What is Inner Join?
What is Self Join?
What is Natural Join?

5 Marks

Explain Inner Join with example.
Explain Left Join and Right Join.
Explain Self Join.

7 Marks

Explain different types of SQL Joins.
Differentiate Inner Join and Outer Join.
Explain Join operations with examples.

14 Marks

Explain SQL Joins in detail. Discuss Inner Join, Left Join, Right Join, Full Outer Join, Natural Join and Self Join with syntax and examples.

Nested Queries (Subqueries)

Nested Query ya Subquery ek query ke andar likhi gayi doosri query hoti hai.

Jab kisi query ka result doosri query me use hota hai, tab Nested Query ka use kiya jata hai.

RGPV exams me Nested Queries se frequently programming aur theory based questions pooche jate hain.

Definition

A Nested Query is a query embedded inside another SQL query.

Basic Structure

Outer Query ↓ (Sub Query) ↓ Result

Student Table

Roll_No	Name	Marks
101	Shivam	85
102	Rahul	70
103	Aman	90

Example 1

Find students having marks greater than average marks.

SELECT Name FROM Student WHERE Marks > ( SELECT AVG(Marks) FROM Student );

Working

Subquery Executes First ↓ AVG(Marks) ↓ 81.67 ↓ Outer Query Executes

Example 2

Find student having maximum marks.

SELECT * FROM Student WHERE Marks = ( SELECT MAX(Marks) FROM Student );

Types of Nested Queries

Nested Queries │ ├── Single Row Subquery ├── Multiple Row Subquery ├── Correlated Subquery └── Nested Subquery

1. Single Row Subquery

Single Row Subquery sirf ek value return karti hai.

Example

SELECT * FROM Student WHERE Marks > ( SELECT AVG(Marks) FROM Student );

2. Multiple Row Subquery

Multiple Row Subquery multiple values return karti hai.

Example

SELECT * FROM Student WHERE Branch IN ( SELECT Branch FROM Department );

3. Correlated Subquery

Correlated Subquery outer query par depend karti hai.

Ye har row ke liye execute hoti hai.

Example

SELECT S1.Name FROM Student S1 WHERE Marks > ( SELECT AVG(Marks) FROM Student S2 WHERE S1.Branch = S2.Branch );

Advantages of Nested Queries

Complex queries ko simplify karti hain.
Readable syntax.
Powerful data retrieval.
Dynamic query execution.

Disadvantages of Nested Queries

Execution slower ho sakti hai.
Complexity increase ho sakti hai.
Large databases me performance issues ho sakte hain.

Views

View ek virtual table hoti hai jo actual table ke data par based hoti hai.

View khud data store nahi karti. Ye sirf query ka result store karti hai.

Definition

A View is a virtual table created from one or more database tables using an SQL query.

Why Views are Needed?

Security provide karne ke liye.
Complex queries simplify karne ke liye.
Data abstraction provide karne ke liye.
Specific users ko limited data dikhane ke liye.

View Architecture

User ↓ View ↓ Actual Table

Create View

Syntax

CREATE VIEW CSE_Students AS SELECT * FROM Student WHERE Branch='CSE';

Using a View

SELECT * FROM CSE_Students;

Example

Roll_No	Name	Branch
101	Shivam	CSE
103	Aman	CSE

Ye view sirf CSE students ko show karegi.

Drop View

Syntax

DROP VIEW CSE_Students;

Advantages of Views

Security improve hoti hai.
Complex queries hide kar sakte hain.
Data abstraction provide karti hain.
Easy maintenance.
Custom user views create kar sakte hain.

Disadvantages of Views

Performance impact ho sakta hai.
Complex views difficult hoti hain.
Har view updateable nahi hoti.

View vs Table

View	Table
Virtual	Physical
No Data Storage	Stores Data
Query Based	Actual Records
Security Purpose	Data Storage Purpose

Nested Query vs View

Nested Query	View
Query Inside Query	Virtual Table
Temporary Result	Reusable Result
Used During Execution	Stored Definition

Memory Trick

Nested Query ↓ Query Inside Query ------------------- View ↓ Virtual Table ------------------- Subquery ↓ Runs First

Exam Shortcut

Concept	Remember
Nested Query	Query Inside Query
View	Virtual Table
CREATE VIEW	Create Virtual Table
DROP VIEW	Delete View

RGPV Exam Keywords

Nested Query
Subquery
Single Row Subquery
Multiple Row Subquery
Correlated Subquery
View
Virtual Table
CREATE VIEW
DROP VIEW
Data Abstraction

Most Expected Questions

2 Marks

What is Nested Query?
What is a View?
Define Virtual Table.
What is Correlated Subquery?

5 Marks

Explain Nested Query with example.
Explain Views with example.
Differentiate View and Table.

7 Marks

Explain different types of Nested Queries.
Explain Views with advantages and disadvantages.
Differentiate Nested Query and View.

14 Marks

Explain Nested Queries and Views in detail with syntax, examples, advantages, disadvantages and comparison.

Integrity Constraints

Integrity Constraints DBMS ke rules hote hain jo database me data ki accuracy, consistency aur reliability maintain karte hain.

Agar Integrity Constraints na ho to database me invalid, duplicate aur inconsistent data store ho sakta hai.

RGPV examinations me Integrity Constraints se frequently 5 marks, 7 marks aur 14 marks ke questions pooche jate hain.

Definition

Integrity Constraints are rules applied on database tables to ensure the correctness, consistency and validity of data.

Why Integrity Constraints are Needed?

Data accuracy maintain karne ke liye.
Invalid entries prevent karne ke liye.
Database consistency maintain karne ke liye.
Duplicate data avoid karne ke liye.
Relationship correctness ensure karne ke liye.

Types of Integrity Constraints

Integrity Constraints │ ├── Domain Constraint ├── Key Constraint ├── Entity Integrity Constraint ├── Referential Integrity Constraint └── NOT NULL Constraint

1. Domain Constraint

Domain Constraint ensure karta hai ki attribute ki value predefined domain ke andar hi ho.

Example

Marks ↓ 0 to 100

Agar koi student ke marks 150 enter kare to Domain Constraint violation hoga.

Valid Values

Marks = 85 Marks = 92 Marks = 75

Invalid Values

Marks = -10 Marks = 150

2. Key Constraint

Key Constraint ensure karta hai ki Primary Key unique ho.

Do records ki Primary Key same nahi ho sakti.

Example

Roll_No	Name
101	Shivam
102	Rahul

Yahaan Roll_No unique hai.

Invalid Example

Roll_No	Name
101	Shivam
101	Rahul

Ye Key Constraint violation hai.

3. Entity Integrity Constraint

Entity Integrity ke according Primary Key kabhi NULL nahi ho sakti.

Rule

Primary Key ≠ NULL

Valid Example

Roll_No	Name
101	Shivam

Invalid Example

Roll_No	Name
NULL	Shivam

Primary Key NULL nahi ho sakti.

4. Referential Integrity Constraint

Referential Integrity Foreign Key aur Primary Key ke relationship ko maintain karti hai.

Rule

Foreign Key value ya to referenced table me exist karegi ya NULL hogi.

Department Table

Dept_ID	Department
D1	CSE
D2	IT

Student Table

Roll_No	Name	Dept_ID
101	Shivam	D1
102	Rahul	D2

Valid Foreign Keys

D1 D2

Invalid Foreign Key

D5

Department table me D5 exist nahi karta.

Ye Referential Integrity violation hai.

5. NOT NULL Constraint

NOT NULL Constraint ensure karta hai ki attribute empty na ho.

Example

Name NOT NULL

Valid

Name = Shivam

Invalid

Name = NULL

SQL Example

CREATE TABLE Student ( Roll_No INT PRIMARY KEY, Name VARCHAR(50) NOT NULL, Marks INT CHECK(Marks <=100) );

Constraint Summary

Constraint	Purpose
Domain Constraint	Valid Values Only
Key Constraint	Unique Records
Entity Integrity	Primary Key Not NULL
Referential Integrity	Valid Foreign Key
NOT NULL	No Empty Values

Advantages of Integrity Constraints

Improves data accuracy.
Maintains consistency.
Prevents duplicate records.
Supports data reliability.
Reduces database errors.
Ensures valid relationships.

Real Life Example

College Database ↓ Roll Number Must Be Unique ↓ Entity Integrity --------------------- Department ID Must Exist ↓ Referential Integrity --------------------- Marks 0 to 100 ↓ Domain Constraint

Memory Trick

Domain ↓ Valid Values ------------------ Key ↓ Unique Values ------------------ Entity ↓ Primary Key Not Null ------------------ Referential ↓ Valid Foreign Key

Exam Shortcut

Constraint	Remember
Domain	Range Check
Key	Unique
Entity	Primary Key ≠ NULL
Referential	Foreign Key Valid

RGPV Exam Keywords

Integrity Constraints
Domain Constraint
Key Constraint
Entity Integrity
Referential Integrity
Primary Key
Foreign Key
NOT NULL
Data Consistency
Data Accuracy

Most Expected Questions

2 Marks

Define Integrity Constraint.
What is Domain Constraint?
What is Entity Integrity?
What is Referential Integrity?

5 Marks

Explain Domain Constraint.
Explain Referential Integrity.
Explain Key Constraint.

7 Marks

Explain various Integrity Constraints.
Differentiate Entity Integrity and Referential Integrity.
Explain Integrity Constraints with examples.

14 Marks

Explain Integrity Constraints in DBMS. Discuss Domain Constraint, Key Constraint, Entity Integrity and Referential Integrity with suitable examples.

DBMS Unit 2 Important Questions

The following questions are selected based on RGPV previous year examination patterns, repeated university questions and expected topics for upcoming examinations.

🔥 Top Important 2 Marks Questions

Define Relational Model.

What is a Tuple?

What is an Attribute?

Define Relational Algebra.

What is SQL?

Define DDL.

Define DML.

What is DCL?

What is TCL?

What is a View?

What is Referential Integrity?

What is Inner Join?

⭐ Top Important 5 Marks Questions

Explain Relational Model with example.

Explain Selection and Projection operations.

Differentiate Relational Algebra and Relational Calculus.

Explain SQL architecture.

Explain DDL commands with examples.

Explain DML commands with examples.

Explain GRANT and REVOKE commands.

Explain COMMIT and ROLLBACK.

Explain SQL Joins.

Explain Views in DBMS.

🏆 Top Important 7 Marks Questions

Explain Relational Model and its terminology.

Explain Relational Algebra operations with examples.

Explain Tuple Relational Calculus and Domain Relational Calculus.

Discuss SQL and its components.

Explain DDL and DML commands with syntax.

Explain DCL and TCL commands.

Explain different types of SQL Joins.

Explain Nested Queries with examples.

Explain Integrity Constraints.

Differentiate View and Table.

🚀 Most Important 14 Marks Questions

Explain Relational Model in detail with keys and examples.

Explain Relational Algebra operations with suitable examples.

Explain Relational Calculus and its types.

Explain SQL and its components with examples.

Explain DDL, DML, DCL and TCL commands.

Explain SQL Joins with syntax and examples.

Explain Nested Queries and Views.

Explain Integrity Constraints with examples.

DBMS Unit 2 PYQ Analysis

The following analysis is based on RGPV Previous Year Question Papers (2020, 2022, 2023 and 2025). These topics have appeared repeatedly in university examinations and are highly important for upcoming exams.

Topics Covered

Relational Model

Relational Algebra

SQL

SQL Joins

Nested Queries

Views

Integrity Constraints

PYQ Frequency Analysis

Topic	2020	2022	2023	2025	Frequency
Relational Algebra	✅	✅	✅	✅	★★★★★
SQL Queries	✅	✅	✅	✅	★★★★★
SQL Joins	❌	✅	✅	✅	★★★★★
Referential Integrity	❌	✅	✅	❌	★★★★☆
Views	❌	❌	❌	Short Note	★★★☆☆
Relational Model	❌	SQL Based	SQL Based	SQL Based	★★★★☆

Most Repeated Unit 2 Questions

🔥 Q1. Write Relational Algebra Expressions

Appeared In:

2022
2023
2025

Prediction: ⭐⭐⭐⭐⭐

🔥 Q2. Write SQL Queries for Given Database

Appeared In:

2020
2022
2023
2025

Prediction: ⭐⭐⭐⭐⭐

🔥 Q3. Explain Foreign Key and Referential Integrity

Appeared In:

2022
2023

Prediction: ⭐⭐⭐⭐⭐

🔥 Q4. Natural Join / Outer Join Questions

Appeared In:

2023
2025

Prediction: ⭐⭐⭐⭐⭐

🔥 Q5. Views in DBMS

Appeared In:

2023 (Short Note)

Prediction: ⭐⭐⭐⭐☆

2026 Expected Questions

VERY HIGH PROBABILITY 🔥 Relational Algebra Operations 🔥 SQL Queries 🔥 SQL Joins 🔥 Referential Integrity 🔥 Relational Schema Based Questions -------------------------------- HIGH PROBABILITY ⭐ Views ⭐ Nested Queries ⭐ DDL Commands ⭐ DML Commands ⭐ Integrity Constraints

Actual RGPV Trend

If questions are asked from Unit 2, the following topics have appeared most frequently in RGPV examinations:

1. SQL Queries 2. Relational Algebra 3. SQL Joins 4. Referential Integrity 5. Relational Schema Problems

These five topics have appeared in almost every previous year paper either directly or indirectly.

Unit 2 Weightage Analysis

Topic	Importance
SQL Queries	★★★★★
Relational Algebra	★★★★★
SQL Joins	★★★★★
Referential Integrity	★★★★★
Relational Schema Problems	★★★★★
Nested Queries	★★★★☆
Views	★★★★☆
DDL & DML Commands	★★★★☆
Integrity Constraints	★★★★☆
Relational Model	★★★★☆

2026 Score Booster Topics

✓ Relational Algebra ✓ SQL Queries ✓ SQL Joins ✓ Referential Integrity ✓ Relational Schema Problems ✓ Nested Queries ✓ Views ✓ Integrity Constraints

If you prepare these topics thoroughly, you can cover approximately 75-85% of the repeated RGPV Unit 2 question pattern.

Frequently Asked Questions (FAQs)

What is Relational Model?

Relational Model is a database model in which data is stored in the form of tables called relations.

What is Relational Algebra?

Relational Algebra is a procedural query language used to retrieve and manipulate data from relational databases.

What is Relational Calculus?

Relational Calculus is a non-procedural query language that specifies what data is required rather than how to retrieve it.

What is SQL?

SQL (Structured Query Language) is a standard language used to create, retrieve, update and manage data in relational databases.

What is a Join?

A Join is an SQL operation used to combine records from two or more tables based on a common field.

What is a View?

A View is a virtual table created from one or more database tables using an SQL query.

What is a Nested Query?

A Nested Query or Subquery is a query written inside another SQL query.

What are Integrity Constraints?

Integrity Constraints are rules used to maintain accuracy, consistency and reliability of database data.

What is Entity Integrity?

Entity Integrity ensures that the Primary Key can never contain NULL values.

What is Referential Integrity?

Referential Integrity ensures that every Foreign Key value refers to a valid Primary Key value.

DBMS Unit 2 Quick Revision Sheet

RELATIONAL MODEL ↓ Relation = Table Tuple = Row Attribute = Column Domain = Allowed Values Degree = Number of Columns Cardinality = Number of Rows -------------------------------- RELATIONAL ALGEBRA ↓ Selection (σ) Projection (π) Union (∪) Intersection (∩) Difference (-) Join (⨝) Cartesian Product (×) -------------------------------- RELATIONAL CALCULUS ↓ TRC DRC Non-Procedural Language -------------------------------- SQL ↓ DDL DML DCL TCL -------------------------------- DDL ↓ CREATE ALTER DROP TRUNCATE -------------------------------- DML ↓ INSERT SELECT UPDATE DELETE -------------------------------- DCL ↓ GRANT REVOKE -------------------------------- TCL ↓ COMMIT ROLLBACK SAVEPOINT -------------------------------- JOINS ↓ Inner Join Left Join Right Join Full Join Natural Join Self Join -------------------------------- INTEGRITY CONSTRAINTS ↓ Domain Constraint Key Constraint Entity Integrity Referential Integrity NOT NULL

Last Minute Exam Revision

Topic	Priority
Relational Algebra	★★★★★
SQL Commands	★★★★★
SQL Joins	★★★★★
Integrity Constraints	★★★★★
Relational Model	★★★★★
Views	★★★★☆
Nested Queries	★★★★☆
DCL & TCL	★★★★☆
Relational Calculus	★★★★☆

Most Important Definitions for Exam

Relational Model ↓ Data Stored in Tables -------------------------------- Relational Algebra ↓ Procedural Query Language -------------------------------- Relational Calculus ↓ Non-Procedural Query Language -------------------------------- SQL ↓ Structured Query Language -------------------------------- Join ↓ Combine Tables -------------------------------- View ↓ Virtual Table -------------------------------- Entity Integrity ↓ Primary Key Cannot Be NULL -------------------------------- Referential Integrity ↓ Valid Foreign Key

Related DBMS Units

DBMS Unit 1 DBMS Unit 3 DBMS Unit 4 DBMS Unit 5

Conclusion

DBMS Unit 2 introduces students to the practical implementation of relational databases. In this unit we studied Relational Model, Relational Algebra, Relational Calculus, SQL Commands, Joins, Nested Queries, Views and Integrity Constraints.

These concepts form the foundation of database programming and are extensively used in web development, software engineering, backend development and enterprise database systems.

🏆 UNIT 2 SCORE BOOSTER Must Prepare: ✓ Relational Model ✓ Relational Algebra ✓ SQL Commands ✓ SQL Joins ✓ Integrity Constraints ✓ Views These topics cover most of the repeatedly asked RGPV examination questions.

DBMS Unit 2 Notes

Relational Model, SQL, Relational Algebra and Integrity Constraints

Detailed Notes

Important Questions

PYQ Analysis

DBMS Unit 2 Syllabus Topics

What You Will Learn in DBMS Unit 2?

DBMS Unit 2 Notes

Relational Model, SQL, Relational Algebra and Integrity Constraints

Detailed Notes

Important Questions

PYQ Analysis

DBMS Unit 2 Syllabus Topics

What You Will Learn in DBMS Unit 2?

Relational Algebra

Definition

Why Relational Algebra is Important?

Basic Concept

Types of Operations

Student Relation Example

1. Selection Operation (σ)

Symbol

Example

2. Projection Operation (π)

Symbol

Example

3. Union Operation (∪)

Example

Conditions for Union

4. Set Difference Operation (-)

Example

5. Intersection Operation (∩)

Example

6. Cartesian Product (×)

Example

Formula

7. Join Operation (⨝)

Example

Types of Join

8. Division Operation (÷)

Example of Division

Advantages of Relational Algebra

Disadvantages of Relational Algebra

Summary Table

Memory Trick

RGPV Exam Keywords

Most Expected Questions

2 Marks

5 Marks

7 Marks

14 Marks

Relational Calculus

Definition

Basic Concept

Procedural vs Non-Procedural Language

Types of Relational Calculus

1. Tuple Relational Calculus (TRC)

General Form

Example

Student Relation

Advantages of TRC

2. Domain Relational Calculus (DRC)

General Form

Example

TRC vs DRC

Free Variables

Bound Variables

Quantifiers in Relational Calculus

Universal Quantifier (∀)

Example:

Existential Quantifier (∃)

Example:

Advantages of Relational Calculus

Disadvantages of Relational Calculus

Relational Algebra vs Relational Calculus

Memory Trick

RGPV Exam Keywords

Most Expected Questions

2 Marks

5 Marks