DBMS PRACTICE QUESTIONS

Duration: 5 min

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Inside: a video lesson and guided study material.

Module outline

  1. Communication Round: Vocabulary, Subject Verb Agreement (Verb Noun Agreement), Tenses, Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Cloze Test (Cloze Passage), Sentence Correction (Error Correction), Sentence Completion (Fill in the blanks), Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Direct and Indirect Speech, Active Passive Voice (Voice), Verbal Analogy (Word Based Analogy), Articles, Preposition, Conjunction, Sentence Construction, English Writing Ability, Communication Assessment
  2. Quantitative Aptitude: Ratio and Proportion (Ratios), Divisibility Rules, Data Interpretation, Mixture and Alligation, Permutation and Combination, Logarithm, Number System, HCF LCM, Speed Time and Distance, Percentage, Average, Powers and Exponents (Surds and Indices), Time and Work, Mensuration and Geometry, Age Problems, Pipe and Cistern, Probability, Profit and Loss, Simple Interest and Compound Interest, Algebra
  3. Analytical and Logical Reasoning: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Directions (Direction Test), Ranking, Order and Sequence, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Selection Decision Table (Decision Making), Logical Sequence Of Words, Puzzle Solving (Puzzles), Syllogisms, Seating Arrangements, Calendar, Clock, Blood Relations, Cubes & Dices, Venn Diagram, Analytical Reasoning (Counting Figures Reasoning)
  4. Cognizant Gaming Aptitude: Gamified / Game Based Aptitude
  5. Java (Cluster 1): Java
  6. ANSI SQL MySQL (Cluster 1,2,3): SQL
  7. HTML, CSS, JavaScript (Cluster 1,3): HTML, CSS, JavaScript
  8. Python (Cluster 2): Python for Placements by Yash Sir
  9. Cloud Fundamentals (Cluster 2): Emerging Tech Trends
  10. C# (Cluster 3): C#
  11. OOPs: Object Oriented Programming (OOPS)
  12. Technical Assessment (Coding): Coding Questions by Yash Sir, C Programming by Yash Sir, Programming in C++, Pseudo Codes
  13. Data Structures: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  14. DBMS: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, Relational Calculus, Transaction Management, Concurrency Control, Database Recovery, ORDBMS, Database Security & Authorization, Query Processing & Optimization, Enhanced Data Models, Data Warehousing & Mining, Big Data Systems, NoSQL
  15. Operating Systems: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Windows OS, Linux OS, Security, Distributed Systems, Virtual Machines
  16. Computer Networks: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, DLL: Framing, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Net Layer:Routing Protocol, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware basics, Network Security, Mobile Technology, Cloud Computing and IoT, Cyber and Info Security
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The video is an educational lecture on database theory, specifically focusing on the process of finding candidate keys for a relational schema. The problem presented is R(WXYZ) with a set of functional dependencies: X -> W, WZ -> XY, and Y -> WXZ. The instructor systematically applies the attribute closure method to determine which attribute sets can function as candidate keys. He begins by testing individual attributes and small combinations, calculating their closures to see if they encompass all attributes in the relation. The lecture progresses from identifying obvious keys to using heuristics for finding multiple candidate keys, culminating in a final list of keys.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor starts by writing the problem statement "Q. R(WXYZ) Find candidate key" and listing the functional dependencies: X -> W, WZ -> XY, and Y -> WXZ. He begins the analysis by calculating the closure of X, denoted as X+, which he writes as {X, W}. He notes that this is not a superkey because it lacks Y and Z. Next, he calculates the closure of the combination WZ, writing (WZ)+ = {W, X, Z, Y}. He identifies this as a Super Key (SK) and a Candidate Key (CK). He then checks the subsets W and Z, writing W+ = {W} and Z+ = {Z}, marking them as not keys. Finally, he calculates the closure of Y, writing Y+ = {Y, W, X, Z}, identifying Y as a Candidate Key. He summarizes the candidate keys found so far as {Y, WZ}.

  2. 2:00 – 4:30 02:00-04:30

    The instructor moves on to discuss finding multiple candidate keys. He writes a rule on the board: "To find multiple CKs: X -> PA then X must be apart of any CK". He identifies the Prime Attributes (PA) as {W, Y, Z}. He then explores the combination XZ. He reasons that since X -> W, the set XZ can derive WZ. Since WZ -> XY, XZ can derive all attributes. He writes "CK {Y, WZ, XZ}" on the board. He also writes "X -> Y" and crosses out "X -> W", possibly correcting a dependency or exploring a relationship, but the final boxed answer clearly lists Y, WZ, and XZ as the candidate keys. He boxes the final answer "CK {Y, WZ, XZ}" to conclude the problem.

The lecture provides a clear, step-by-step demonstration of finding candidate keys using attribute closure. It covers the initial identification of keys through direct calculation and then introduces a heuristic method to find additional keys involving prime attributes. The instructor uses board writing to visually track the closure calculations and the final set of candidate keys, ensuring students can follow the logical progression from functional dependencies to the final solution.

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