Consider: int arr[10]; int *p = arr; What is p[5] equivalent to?

The correct answer is C: *(arr + 5) or arr[5]. Array name decays to pointer. p[5] is equivalent to *(p+5) which is *(arr+5) or arr[5]. This demonstrates pointer arithmetic.

What is the output of the following C code? int x = 5; printf("%d", x++);

The correct answer is B: 5. The post-increment operator (x++) returns the current value of x before incrementing. So printf prints 5, and then x becomes 6.

What will be the output of: #define MAX 10; int x = MAX; printf("%d", x);

The correct answer is A: 10. The #define directive replaces MAX with 10 during preprocessing. So x = 10 and output is 10. (Note: semicolon after MAX is not needed but doesn't affect the output)

What will be the result of: int a = 10, b = 3; int c = a % b; printf("%d", c);

The correct answer is B: 1. The modulus operator % returns the remainder of division. 10 % 3 = 1 (since 10 = 3 × 3 + 1). Therefore, c = 1 and the output is 1.

What is the time complexity of quicksort algorithm in the worst case?

The correct answer is B: O(n²). Quicksort's worst-case complexity is O(n²) when pivot selection is poor, though average case is O(n log n).

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Database/SQL

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Difficulty: All Easy Medium Hard 21–30 of 50

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All C Programming 200 Database/SQL 100

Q.21 Medium Database/SQL

What is the normal form that ensures no partial dependencies exist in a relation?

A Third Normal Form (3NF)

B Boyce-Codd Normal Form (BCNF)

C Second Normal Form (2NF)

D First Normal Form (1NF)

Correct Answer: C. Second Normal Form (2NF)

EXPLANATION

2NF eliminates partial dependencies where non-key attributes depend on part of a composite key. 3NF further eliminates transitive dependencies.

Test

Q.22 Medium Database/SQL

What is the time complexity of searching an element in a balanced Binary Search Tree?

A O(n)

B O(n log n)

C O(log n)

D O(1)

Correct Answer: C. O(log n)

EXPLANATION

A balanced BST maintains O(log n) search complexity by keeping the tree height logarithmic relative to node count.

Test

Q.23 Medium Database/SQL

Which encryption standard is currently recommended for securing data in transit over networks?

A DES

B MD5

C TLS 1.3

D SHA-1

Correct Answer: C. TLS 1.3

EXPLANATION

TLS 1.3 is the latest, most secure protocol standard for encrypting data in transit, replacing older protocols like SSL and TLS 1.2.

Test

Q.24 Medium Database/SQL

In machine learning, what is a confusion matrix primarily used for?

A To train neural networks

B To evaluate classification model performance

C To normalize feature scaling

D To generate random datasets

Correct Answer: B. To evaluate classification model performance

EXPLANATION

A confusion matrix shows True Positives, True Negatives, False Positives, and False Negatives, enabling comprehensive evaluation of classification accuracy.

Test

Q.25 Medium Database/SQL

What is the primary benefit of containerization technology like Docker in modern application deployment?

A Reduces application performance

B Ensures consistency between development and production environments

C Eliminates the need for databases

D Automatically handles all security patches

Correct Answer: B. Ensures consistency between development and production environments

EXPLANATION

Docker containers package applications with dependencies, ensuring identical execution across different environments.

Test

Q.26 Medium Database/SQL

In cloud computing, what does the term 'eventual consistency' refer to?

A Data is immediately consistent across all nodes

B Data will become consistent across distributed systems after some time

C Consistency checks are performed eventually

D Cloud systems never achieve consistency

Correct Answer: B. Data will become consistent across distributed systems after some time

EXPLANATION

Eventual consistency in cloud systems means that data replicas will converge to the same state after all updates have propagated.

Test

Q.27 Medium Database/SQL

Which data structure is most efficient for implementing a LRU (Least Recently Used) cache?

A Array

B Hash Map + Doubly Linked List

C Binary Search Tree

D Queue only

Correct Answer: B. Hash Map + Doubly Linked List

EXPLANATION

Hash Map provides O(1) lookup while Doubly Linked List maintains insertion order and allows O(1) removal/reordering.

Test

Q.28 Medium Database/SQL

In SQL, what is the difference between HAVING and WHERE clauses?

A Both serve identical purposes

B WHERE filters rows before grouping; HAVING filters groups after aggregation

C HAVING is used for individual row filtering

D WHERE can only be used with JOIN operations

Correct Answer: B. WHERE filters rows before grouping; HAVING filters groups after aggregation

EXPLANATION

WHERE clause filters individual rows before GROUP BY, while HAVING filters aggregated groups after GROUP BY.

Test

Q.29 Medium Database/SQL

What does CAP theorem state about distributed database systems?

A All three properties can be achieved simultaneously

B Only two of Consistency, Availability, and Partition tolerance can be guaranteed

C Consistency is always sacrificed first

D Partition tolerance is optional in modern systems

Correct Answer: B. Only two of Consistency, Availability, and Partition tolerance can be guaranteed

EXPLANATION

CAP theorem proves that distributed systems can guarantee at most 2 of 3 properties: Consistency, Availability, and Partition tolerance.

Test

Q.30 Medium Database/SQL

Which of the following is NOT a characteristic of relational databases?

A ACID compliance

B Flexible schema

C Structured data storage

D Data integrity constraints

Correct Answer: B. Flexible schema

EXPLANATION

Relational databases have fixed schemas. Flexible schemas are a characteristic of NoSQL databases like MongoDB.

Test

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