PROJECTENGRAM

CONCEPTS-FINALS-MOCK-ANSWERS

Concepts-Finals-Mock-Answers

Tags: #◇CCINFOM #◇Data Modeling #◇Information Structures #◇Computer Science #◇Databases #◇SQL

◇Overview

Subject: Information and Database Management

◇Details / Theory

Concept Finals Mock Exam - ANSWERS

Subject: Information and Database Management

◇Part 1: Multiple Choice

  1. B - Software that manages... (The DBMS is the tool/software, the Database is the collection of data).
  2. C - A Row (Relation = Table, Attribute = Column, Tuple = Row).
  3. B - Physical Data Independence (Physical deals with storage/indexes; Logical deals with schema/tables).
  4. C - Insertion Anomaly (You can't insert the child because the parent doesn't exist or you don't have the data yet).
  5. C - It has no partial dependencies (2NF is about the Whole Key. Partial dependency means depending on only part of a composite key).
  6. A - Atomicity (Atoms are indivisible. The transaction happens fully or not at all).
  7. B - 2NF (StudentName depends only on StudentID, which is part of the composite PK. This is a Partial Dependency).
  8. C - Referential Integrity (Ensures references between tables are valid).
  9. C - An artificial key... (Surrogate keys like Auto-Increment IDs have no business meaning, unlike Natural keys like SSN).
  10. B - The "Many" side... (The three branching lines look like a crow's foot, indicating "Many").

◇Part 2: True or False

  1. FALSE - Primary Keys identify the row; NULL means "unknown", so it can't identify anything. (Entity Integrity).
  2. TRUE - A NULL Foreign Key usually implies an Optional relationship (e.g., an Employee with no Manager).
  3. TRUE - You can have many unique columns (Candidate Keys), but you must choose only one to be the Primary Key.
  4. FALSE - Normalization reduces redundancy. Denormalization increases it.
  5. TRUE - This is the definition of Logical Data Independence.
  6. FALSE - This is a Transitive Dependency, which is forbidden in 3NF.
  7. TRUE - In the Relational Model, a Relation is a Table.
  8. TRUE - Consistency ensures database rules (constraints) are not violated.
  9. FALSE - A Weak Entity depends on the existence of a Strong Entity (Parent) for its identity.
  10. FALSE - SQL is Declarative (Non-procedural). You tell it what you want (SELECT), not how to get it (loops/pointers).

◇Part 3: Identification

  1. Normalization
  2. Composite Key
  3. Transitive Dependency
  4. SQL (Structured Query Language)
  5. Conceptual Model (or Conceptual Schema)

◇Part 4: Advanced Concepts (New Topics)

  1. C - Cartesian Product (Combines every row of A with every row of B).
  2. B - Total Participation (or Completeness Constraint). The double line in ERD.
  3. B - Read Committed (Prevents Dirty Reads, but allows Non-Repeatable Reads).
  4. B - Clustered Index (Sorts the physical data rows).
  5. B - SQL Injection (Malicious code insertion).

◇Part 5: Scenario Analysis

  1. Missing Index
    Analysis: Scanning 1 million rows (Full Table Scan) is slow.
    Fix: Create an Index on the OrderDate column.

  2. Isolation Failure (Race Condition)
    Analysis: The database allowed two transactions to read the same state ("Available") before either committed the change.
    Violation: Isolation (specifically, likely running at a lower isolation level like Read Committed instead of Serializable or Repeatable Read).
    Mechanism: Locking failed (or wasn't used correctly).

◇Part 6: Normalization Analysis

  1. 1NF
    Reason: It violates 2NF because ProductName depends only on ProductID (Partial Dependency), which is just part of the composite Primary Key.
  2. UNF (Unnormalized)
    Reason: It violates 1NF because PhoneNumbers contains multiple values (Repeating Group/Non-atomic).
  3. 2NF
    Reason: It violates 3NF because DeptName depends on DeptID (Transitive Dependency), which is not the Primary Key. It is in 2NF because the PK is a single column, so Partial Dependency is impossible.

◇Common Pitfalls

Accepting short answers without understanding the reasoning — use this key to learn why each answer is correct.
Memorizing answers instead of understanding the underlying concept — exam questions may be rephrased.
Skipping the normalization analysis explanations — they show how to identify UNF/1NF/2NF violations step by step.

◇Summary

TL;DR — Complete answer key with explanations for the Concept-Finals-Mock. Each answer includes a rationale connecting to the underlying DBMS concept.

◇Links

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