Normalization reduces redundancy in OLTP systems.
Normal forms:
- NF: No repeating groups, atomic values
- NF: NF + no partial dependencies on composite keys
- NF: NF + no transitive dependencies
Example violation (NF):
| order_id | product_id | product_name |
product_name depends only on product_id, not the full key.
In analytics: You'll often denormalize deliberately. Know the rules so you can explain when and why you break them.