Free Keys, ER and normalization lessonsKeys, ER and normalization · Stage 3 · Normal forms · Step 1
Anomalies, 1NF, 2NF and 3NF
Why storing a fact twice breaks things, and how the first three normal forms remove each kind of repetition. About 15 minutes.
R(A, B, C) has the single key {A, B} and the dependency A → C. What is the highest normal form it satisfies?
- A1NF: C depends on only part of the key AB
- B2NF
- C3NF
Show the answer
1NF: C depends on only part of the key AB. A partial dependency breaks 2NF, so only 1NF holds.
4 questions on this idea
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