DBMS EXAM CHEAT SHEET 2026 Last Minute Notes
DBMS
LAST MINUTE EXAM NOTES
Complete Cheat Sheet with Examples • 2026 Edition
SQL Normalization Transactions Indexing ER Model NoSQL
Topics: Basics • Keys • ER Model • SQL • Normalization • Transactions • Indexing • Relational Algebra • NoSQL
DBMS Notes 2026 Page 1
,DBMS EXAM CHEAT SHEET 2026 Last Minute Notes
TABLE OF CONTENTS
Quick Navigation Guide
# Topic Key Concepts
01 DBMS Basics Architecture, Instances, DDL/DML/DCL/TCL
02 Keys & Constraints PK, FK, CK, Super Key, Referential Integrity
03 ER Model Entities, Attributes, Cardinality, Conversion
04 SQL Joins, Subqueries, Window Functions, NULLs
05 Normalization 1NF to BCNF, FDs, Armstrong's Axioms, Closure
06 Transactions & ACID ACID, Concurrency Problems, Isolation Levels, 2PL
07 Indexing B+ Tree, Hashing, Dense vs Sparse, RAID
08 Relational Algebra σ π ∪ ∩ − × ■ ÷ with examples
09 NoSQL & Misc CAP Theorem, Recovery, Query Optimization
DBMS Notes 2026 Page 2
, DBMS EXAM CHEAT SHEET 2026 Last Minute Notes
DBMS BASICS
01 Foundation concepts — always in exam
What is DBMS?
A Database Management System (DBMS) is software that stores, manages, organizes, and retrieves data efficiently with
security and consistency. Examples: MySQL, Oracle, PostgreSQL, MongoDB, SQLite.
NOTE File System problems solved by DBMS: data redundancy, inconsistency, no concurrent access, no security, no backup/recovery
3-Level Architecture (ANSI/SPARC) — Very Important
Level Name What it Contains Example
External View Level What each user sees (subset) Student sees only their marks
Conceptual Logical Level Full logical structure of DB Tables, attributes, relationships
Internal Physical Level How data is stored on disk File paths, block sizes, indexes
TIP Data Independence: Logical = change schema without affecting apps. Physical = change storage without affecting schema.
Schema vs Instance
Schema = Blueprint/structure of the DB (changes rarely) Instance = Actual data at a point in time (changes often)
Example: Student(RollNo, Name, Marks, Dept) Example: (101, 'Arjun', 85, 'CSE')
Defined using DDL commands Manipulated using DML commands
DDL / DML / DCL / TCL — Command Classification
Category Full Form Commands Purpose
DDL Data Definition Language CREATE, ALTER, DROP, TRUNCATE, RENAME Define/modify structure
DML Data Manipulation Language SELECT, INSERT, UPDATE, DELETE Manipulate data
DCL Data Control Language GRANT, REVOKE Access control & permissions
TCL Transaction Control Language COMMIT, ROLLBACK, SAVEPOINT Manage transactions
EXAM TRAP TRUNCATE is DDL (cannot rollback) but DELETE is DML (can rollback). This is a classic exam trap!
DBMS Notes 2026 Page 3
DBMS
LAST MINUTE EXAM NOTES
Complete Cheat Sheet with Examples • 2026 Edition
SQL Normalization Transactions Indexing ER Model NoSQL
Topics: Basics • Keys • ER Model • SQL • Normalization • Transactions • Indexing • Relational Algebra • NoSQL
DBMS Notes 2026 Page 1
,DBMS EXAM CHEAT SHEET 2026 Last Minute Notes
TABLE OF CONTENTS
Quick Navigation Guide
# Topic Key Concepts
01 DBMS Basics Architecture, Instances, DDL/DML/DCL/TCL
02 Keys & Constraints PK, FK, CK, Super Key, Referential Integrity
03 ER Model Entities, Attributes, Cardinality, Conversion
04 SQL Joins, Subqueries, Window Functions, NULLs
05 Normalization 1NF to BCNF, FDs, Armstrong's Axioms, Closure
06 Transactions & ACID ACID, Concurrency Problems, Isolation Levels, 2PL
07 Indexing B+ Tree, Hashing, Dense vs Sparse, RAID
08 Relational Algebra σ π ∪ ∩ − × ■ ÷ with examples
09 NoSQL & Misc CAP Theorem, Recovery, Query Optimization
DBMS Notes 2026 Page 2
, DBMS EXAM CHEAT SHEET 2026 Last Minute Notes
DBMS BASICS
01 Foundation concepts — always in exam
What is DBMS?
A Database Management System (DBMS) is software that stores, manages, organizes, and retrieves data efficiently with
security and consistency. Examples: MySQL, Oracle, PostgreSQL, MongoDB, SQLite.
NOTE File System problems solved by DBMS: data redundancy, inconsistency, no concurrent access, no security, no backup/recovery
3-Level Architecture (ANSI/SPARC) — Very Important
Level Name What it Contains Example
External View Level What each user sees (subset) Student sees only their marks
Conceptual Logical Level Full logical structure of DB Tables, attributes, relationships
Internal Physical Level How data is stored on disk File paths, block sizes, indexes
TIP Data Independence: Logical = change schema without affecting apps. Physical = change storage without affecting schema.
Schema vs Instance
Schema = Blueprint/structure of the DB (changes rarely) Instance = Actual data at a point in time (changes often)
Example: Student(RollNo, Name, Marks, Dept) Example: (101, 'Arjun', 85, 'CSE')
Defined using DDL commands Manipulated using DML commands
DDL / DML / DCL / TCL — Command Classification
Category Full Form Commands Purpose
DDL Data Definition Language CREATE, ALTER, DROP, TRUNCATE, RENAME Define/modify structure
DML Data Manipulation Language SELECT, INSERT, UPDATE, DELETE Manipulate data
DCL Data Control Language GRANT, REVOKE Access control & permissions
TCL Transaction Control Language COMMIT, ROLLBACK, SAVEPOINT Manage transactions
EXAM TRAP TRUNCATE is DDL (cannot rollback) but DELETE is DML (can rollback). This is a classic exam trap!
DBMS Notes 2026 Page 3
