What is the primary idea of First Normal Form (1NF) in relational databases?

• A. All columns contain atomic (indivisible) values, and each row is unique.
• B. All columns must be non-null.
• C. Each table must have a primary key.
• D. Data must be stored in binary format.

Answer: (A)

First Normal Form is about making every field atomic and every row unique. Atomic means each cell holds a single, indivisible value—not a list or a set. If an attribute would need multiple values, you split them into separate rows or place them in another related table. At the same time, a 1NF table should have no duplicate rows, so each record is identifiable by its values. For example, storing several phone numbers in one column as a comma-separated string breaks atomicity; you’d instead have separate rows for each number or a separate related table linking numbers to the person. This concept focuses on clean, indivisible data and unique records, while other aspects like non-null requirements or a declared primary key are practical considerations that can support but are not the defining feature of 1NF.