Lesson 26 / 30
Normalization at a Glance
Reduce duplicate data with 1NF, 2NF and 3NF, and know when deliberate denormalization is justified.
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.