The printf() function is defined in the Standard Input/Output library. Therefore, '#include <stdio.h>' must be included at the beginning of the program to use printf() and other I/O functions like scanf(), getchar(), putchar(), etc.

3NF removes transitive dependencies where a non-key attribute depends on another non-key attribute. BCNF is stricter but 3NF is the standard answer for eliminating transitive dependencies.

Binary search divides the search space in half with each iteration, resulting in logarithmic time complexity O(log n).

DROP removes the entire table structure and data. DELETE removes only data. TRUNCATE removes data but is faster than DELETE.

Hash collisions occur when two different keys hash to the same table index. Resolution techniques include chaining and open addressing.

Relational databases store structured data in tables. Unstructured data is typically stored in NoSQL or document databases.

ACID properties ensure reliable database transactions: Atomicity (all-or-nothing), Consistency (valid state), Isolation (concurrent independence), Durability (permanent storage).

MongoDB is a NoSQL document database that handles unstructured and semi-structured data efficiently, unlike relational databases like PostgreSQL, Oracle, and MySQL.

ACID properties ensure reliable database transactions: Atomicity (all-or-nothing), Consistency (valid state), Isolation (concurrent independence), and Durability (permanent storage).