Third Normal Form (3NF)
A table is in 3NF if:
- It is in 2NF
- No transitive dependencies (non-prime → non-prime)
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3NF and BCNF
Learning Objectives
- •Identify transitive dependencies
- •Apply 3NF
- •Understand BCNF
Lesson Outline
LearnStep 1/2
3NF and BCNF
Boyce-Codd Normal Form (BCNF)
A table is in BCNF if:
- It is in 3NF
- For every dependency X → Y, X is a super key
3NF allows: A → B where A is prime (part of candidate key)
BCNF requires: A must be a super key for any A → B
BCNF Violation Example
Comparison
| Normal Form | Requirement |
|---|---|
| 1NF | Atomic values, no repeating groups |
| 2NF | 1NF + no partial dependencies |
| 3NF | 2NF + no transitive dependencies |
| BCNF | Every determinant is a super key |