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Third Normal Form
Formal Presentation
Example
- For R2
- There are two kinds of nontrivial functional dependencies in F+:
- Those with (house-num, street, city, state) as a subset of the left hand side of the FD: As (house-num, street, city, state) is a superkey for R2, then functional dependencies satisfy the second condition for 3NF
- Those of the form {zip} {state} where
- For any such functional dependency:
- ( {state}) – ( {zip}) = {state} (or = )
- Because state is a candidate key of R2, such functional dependencies satisfy the third condition for 3NF
Notes: