Functional Dependencies
A functional dependency X → Y means: if two tuples have the same X value, they must have the same Y value.
0:00
0% complete
LearnStep 1 of 2
Functional Dependencies
Learning Objectives
- •Define functional dependencies
- •Identify keys
- •Apply Armstrong's axioms
Lesson Outline
LearnStep 1/2
Functional Dependencies
Types of Keys
- Super Key: Set of attributes that uniquely identifies a tuple
- Candidate Key: Minimal super key (no subset is a key)
- Primary Key: Chosen candidate key
- Prime Attribute: Attribute in any candidate key
- Non-prime Attribute: Not in any candidate key