Lesson 25 / 28

Normalization at a Glance

1NF, 2NF, 3NF — reducing duplicate data.

1NF: atomic values

1NF requires each column to hold a single, atomic value — no comma-separated lists crammed into one cell.

2NF & 3NF

2NF removes columns that only depend on part of a composite key. 3NF removes columns that depend on another non-key column instead of the key itself.

Normalize, then denormalize if needed

Design normalized first for data integrity; only denormalize (duplicate data) later, deliberately, for a proven performance need.