nf12 - Normalization Overview An introduction Nonloss...

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Normalization
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Overview b An introduction b Nonloss decomposition b Functional dependencies b Normal Forms [NF] s First Normal Form – 1NF s Second Normal Form – 2NF s Third Normal Form – 3NF
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Normalization b Normalization first proposed by Codd (1972) b Normalization : The process of decomposing unsatisfactory "bad" relations by breaking up their attributes into smaller relations b Codd proposed 1NF, 2NF, 3NF (normal form) b Functional dependence forms the basis for Codd's original three normal forms, as well as for BCNF b Normalization involves decomposing a given relvar into other relvars, and that decomposition is required to be reversible
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Normalization b Two properties must be preserved in the process of normalization s Lossless join s Dependency preservation b The lossless join or nonadditive property guarantees that the spurious tuples does not occur and no information loss should happen w.r.t. the relational schemas created after decomposition b The dependency preservation property ensures that each Functional Dependency is preserved in the resulting relations
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Nonloss (lossless) decomposition b Case a : no information is lost. b Case b : information is lost. Second decomposition is lossy.
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nf12 - Normalization Overview An introduction Nonloss...

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