Identify incorrect statement about primary keys
Company: Bitkernel
Role: Software Engineer
Category: Software Engineering Fundamentals
Difficulty: medium
Interview Round: Online Assessment
In a relational database, which of the following statements about **primary keys** is **incorrect**?
Options:
- A. Every column that is part of the primary key must be NOT NULL.
- B. Every column that is part of the primary key must be unique.
- C. A table can define only one primary key.
- D. Primary keys can be defined at either the table level or the column level.
Quick Answer: This question evaluates understanding of primary keys and related schema constraints in relational databases, measuring competency in data integrity, uniqueness, NULLability, composite keys, and constraint definition within the Software Engineering Fundamentals domain.