Database Management Systems (CS 401) - Semester 4 BCA at NCE

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Overview

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Why it matters

Every app stores data. Instagram photos, Netflix watchlists, banking transactions — all in databases. DBMS is THE most practical CS subject. What you learn Monday, you use in projects Tuesday.

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Placement relevance

90% of developer roles require SQL. Backend interviews test database design, query optimization, normalization. Top skill on job postings after DSA. Service companies heavily test DBMS (40% of technical questions).

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Prerequisites for

Backend Development · Data Engineering · Big Data · NoSQL Databases · Cloud Databases · Data Warehousing · Business Intelligence

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Recommended books

Database System Concepts by Silberschatz, Korth, and Sudarshan · Fundamentals of Database Systems by Elmasri and Navathe · Database Management Systems by Raghu Ramakrishnan and Johannes Gehrke

Curriculum — 4 Units

U1

Unit 1 · 7 Topics · 0% complete

Database Fundamentals & ER Model

⚡ Key Formulae

Relationship Types:One-to-One (1:1), One-to-Many (1:N), Many-to-Many (M:N)

Participation:Total (double line), Partial (single line)

DBMS Architecture

Data Models

ER Diagrams

Entity & Attributes

Relationships

Cardinality Mapping

Weak Entity Sets

U2

Unit 2 · 7 Topics · 0% complete

Relational Model & SQL

⚡ Key Formulae

Relational Algebra:σ (Select), π (Project), ⨝ (Join), ∪ (Union), - (Difference), × (Cartesian)

JOIN Types:INNER, LEFT OUTER, RIGHT OUTER, FULL OUTER, CROSS, SELF

Relations & Schemas

Keys (Primary, Foreign, Candidate, Super)

Relational Algebra

SQL SELECT Queries

JOIN Operations

Aggregate Functions

Subqueries

U3

Unit 3 · 7 Topics · 0% complete

Normalization & Functional Dependencies

⚡ Key Formulae

Armstrong's Axioms:Reflexivity, Augmentation, Transitivity

BCNF:For every FD A→B, A must be superkey

Functional Dependencies

Armstrong's Axioms

Closure of Attributes

Normal Forms (1NF, 2NF, 3NF, BCNF)

Decomposition

Lossless Join

Dependency Preservation

U4

Unit 4 · 7 Topics · 0% complete

Transactions & Concurrency

⚡ Key Formulae

ACID:Atomicity, Consistency, Isolation, Durability

2PL:Two-Phase Locking: Growing phase, Shrinking phase

ACID Properties

Transaction States

Serializability

Conflict & View Serializability

Locking Protocol

Deadlock Handling

Recovery Techniques

Previous Year Questions

Unit 22023 · End Semester10 marks

Given tables: Employee(EmpID, Name, DeptID, Salary) and Department(DeptID, DeptName, Location). Write SQL queries for: a) List employees earning > avg salary, b) Count employees per department, c) Find departments with no employees.

Unit 32023 · End Semester10 marks

Given relation R(A,B,C,D,E) with FDs: {A→BC, CD→E, B→D, E→A}. Find: a) Candidate keys, b) Highest normal form, c) Decompose into BCNF if needed.

Unit 42022 · End Semester8 marks

Check if the following schedule is conflict serializable: T1: R(A), W(A), R(B), W(B); T2: R(A), W(A), R(C), W(C). Draw precedence graph.

Exam Strategy

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SQL queries = 30-40% marks

Practice writing queries BY HAND. Common questions: JOIN, GROUP BY, HAVING, nested queries. Syntax matters — wrong keyword = zero marks. Practice at least 50 queries.

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Find candidate keys correctly

Normalization questions always ask for candidate keys. Method: 1) Find attributes not on RHS of any FD (must be in key), 2) Compute closure, 3) Check all combinations. Show steps clearly.

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Draw ER diagrams neatly

Use proper symbols: Rectangle (entity), Oval (attribute), Diamond (relationship), Double rectangle (weak entity). Label cardinality (1:1, 1:N, M:N). Neat diagram = better marks.

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ACID properties — memorize scenarios

Questions ask 'Which ACID property is violated?' Know examples: Atomicity (partial transaction), Consistency (constraints), Isolation (concurrent access), Durability (system crash).

Related Subjects

Semester 2

Data Structures

CS 102

Semester 4

Operating Systems

CS 402

Semester 7

Big Data Analytics

CS 701