Showing 211–220 of 309 questions
What is the time complexity of a binary search algorithm on a sorted array?
A
O(n)
B
O(log n)
C
O(n²)
D
O(n log n)
Correct Answer:
B. O(log n)
Explanation:
Binary search divides the search space in half with each iteration, resulting in logarithmic time complexity O(log n).
Which SQL command is used to remove a table structure along with its data?
A
DELETE
B
DROP
C
TRUNCATE
D
REMOVE
Explanation:
DROP removes the entire table structure and data. DELETE removes only data. TRUNCATE removes data but is faster than DELETE.
In a hash table, what is the primary cause of collision?
A
Two different keys hashing to the same index
B
Insufficient memory allocation
C
Poor sorting algorithm
D
Network latency issues
Correct Answer:
A. Two different keys hashing to the same index
Explanation:
Hash collisions occur when two different keys hash to the same table index. Resolution techniques include chaining and open addressing.
Which of the following is NOT a characteristic of a relational database?
A
Uses tables with rows and columns
B
Enforces ACID properties
C
Supports unstructured data storage by default
D
Uses primary keys for unique identification
Correct Answer:
C. Supports unstructured data storage by default
Explanation:
Relational databases store structured data in tables. Unstructured data is typically stored in NoSQL or document databases.
What does the acronym ACID stand for in database transactions?
A
Atomicity, Consistency, Isolation, Durability
B
Access, Control, Integration, Distribution
C
Accuracy, Completeness, Integrity, Detection
D
Authorization, Concurrency, Indexing, Duration
Correct Answer:
A. Atomicity, Consistency, Isolation, Durability
Explanation:
ACID properties ensure reliable database transactions: Atomicity (all-or-nothing), Consistency (valid state), Isolation (concurrent independence), Durability (permanent storage).
Q.216
Medium
Database/SQL
Which data structure is best suited for implementing a priority queue?
A
Stack
B
Queue
C
Heap
D
Linked List
Explanation:
A heap (binary heap) efficiently implements priority queues with O(log n) insertion and deletion of minimum/maximum elements.
Q.217
Medium
Database/SQL
In SQL, what is the difference between INNER JOIN and LEFT JOIN?
A
INNER JOIN returns all rows; LEFT JOIN returns only matching rows
B
INNER JOIN returns only matching rows; LEFT JOIN returns all rows from left table
C
Both are identical in functionality
D
INNER JOIN is faster than LEFT JOIN always
Correct Answer:
B. INNER JOIN returns only matching rows; LEFT JOIN returns all rows from left table
Explanation:
INNER JOIN returns only rows with matches in both tables. LEFT JOIN returns all rows from the left table plus matching rows from the right table.
Q.218
Medium
Database/SQL
Which cloud service model provides virtualized computing resources over the internet?
A
SaaS (Software as a Service)
B
IaaS (Infrastructure as a Service)
C
PaaS (Platform as a Service)
D
DaaS (Database as a Service)
Correct Answer:
B. IaaS (Infrastructure as a Service)
Explanation:
IaaS provides infrastructure resources (compute, storage, networking). SaaS provides applications, PaaS provides development platforms.
Q.219
Medium
Database/SQL
What is the primary purpose of database indexing?
A
Increase storage space
B
Improve query performance
C
Reduce security vulnerabilities
D
Eliminate data redundancy
Correct Answer:
B. Improve query performance
Explanation:
Indexes speed up data retrieval by creating optimized lookup structures, reducing the number of disk accesses needed to find data.
Q.220
Medium
Database/SQL
In cybersecurity, what does encryption primarily protect against?
A
Physical theft of devices
B
SQL injection attacks
C
Unauthorized access to data during transmission
D
Database schema changes
Correct Answer:
C. Unauthorized access to data during transmission
Explanation:
Encryption converts data into unreadable format, protecting it from unauthorized access during transmission and storage.
