Minimal keysWe have the attributes: {A, B, C, D}.Consider the following functional dependenciesA, B -> CA, C -> BB, D -> A, CA, B, D -> CC -> A, DFind all minimal keys.
Question
Minimal keysWe have the attributes: {A, B, C, D}.Consider the following functional dependenciesA, B -> CA, C -> BB, D -> A, CA, B, D -> CC -> A, DFind all minimal keys.
Solution
To find all minimal keys, we need to follow these steps:
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Identify all attributes that are not on the right side of any functional dependency. These attributes will be part of every key. In this case, the attribute B is not on the right side of any functional dependency, so B is part of every key.
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For each remaining attribute, check if it can be determined by the attributes already in the key. If it can, it is not part of the key. If it cannot, it is part of the key.
- A: A can be determined by B and D (from B, D -> A), so A is not part of the key.
- C: C can be determined by A and B (from A, B -> C), but A is not part of the key, so C is part of the key.
- D: D can be determined by C (from C -> A, D), so D is not part of the key.
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The minimal keys are the combinations of the attributes in the key. In this case, the only minimal key is {B, C}.
Similar Questions
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