In 1NF, which property describes the indivisibility of each value in a column?

• A. Atomicity of column values
• B. Nullability constraint
• C. Foreign key constraint
• D. Denormalization

Answer: (A)

In 1NF, values in a column must be atomic, meaning each cell holds a single, indivisible value. This ensures every field contains one piece of information, not a list or multiple items. If a column could contain multiple values (like several phone numbers in one field), it would violate 1NF and complicate querying and constraints. The usual way to satisfy 1NF is to store each value separately or in a related table, so each cell remains atomic.

Projects that discuss nullability, foreign keys, or denormalization aren’t about this indivisibility requirement. Nullability deals with whether a value can be missing, a foreign key enforces referential integrity between tables, and denormalization is a design choice that can introduce redundancy. The atomicity of column values is the property that defines 1NF’s rule about indivisible data in each cell.