A relation schema R is in Boyce-Codd Normal Form (BCNF)
if whenever a FD X -> A holds in R, then X is a superkey of R
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Each normal form is strictly stronger than the previous one:
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Every 2NF relation is in 1NF
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Every 3NF relation is in 2NF
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Every BCNF relation is in 3NF
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There exist relations that are in 3NF but not in BCNF
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The goal is to have each relation in BCNF (or 3NF)
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Additional criteria may be needed to ensure the the set of relations
in a relational database are satisfactory (see Chapter 13)
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Dependency preservation property
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Additional normal forms are discussed in Chapter 13
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4NF (based on multi-valued dependencies)
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5NF (based on join dependencies)
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(a) BCNF normalization with the dependency of fd2 being "lost"in the decomposition.
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(b) A relation R in 3NF but not in BCNF.
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