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LOGO Normalization - Relational Databases ENT
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LOGO Your Your site here here Overview Normalization – An introduction Definition of Keys – Recap First Normal Form (1NF) Second Normal Form (2NF) Third Normal Form (3NF) Boyce-Codd Normal Form (BCNF ) B.E. V Sem – Database Management Systems
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LOGO Your Your site here here Normalization Normalization first proposed by Codd (1972) Normalization : The process of decomposing unsatisfactory "bad" relations by breaking up their attributes into smaller relations Normal form : Condition using keys and FDs of a relation to certify whether a relation schema is in a particular normal form Codd proposed 1NF, 2NF, 3NF (normal form) A stronger definition of 3NF – Boyce-Codd normal form (BCNF) – was proposed by Boyce and Codd 2NF, 3NF, BCNF based on keys and FDs of a relation schema B.E. V Sem – Database Management Systems
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LOGO Your Your site here here Normalization The process of decomposition must also confirm the existence of additional properties: (a) The lossless join or nonadditive join property – guarantees that the spurious tuples does not occur w.r.t. the relational schemas created after decomposition (b) The dependency preservation property – ensures that each FD is preserved in the resulting relations Note that property (a) is extremely important and cannot be sacrificed. Property (b) is less stringent and may be sacrificed. B.E. V Sem – Database Management Systems
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Your Your site here here Definition of Keys – Recap A superkey of a relation schema R = { A 1 , A 2 , . ..., A n } is a set of attributes S subset-of R with the property that no two tuples t 1 and t 2 in any legal relation state r of R will have t 1 [ S ] = t 2 [ S ] A key K is a superkey with the additional property that removal of any attribute from K will cause K not to be a superkey any more.
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This note was uploaded on 04/01/2012 for the course CSE,IT 101 taught by Professor Mirunaalini during the Spring '12 term at Indian Institute of Technology, Chennai.

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NF3 - For Evaluation Only. Copyright (c) by VeryPDF.com Inc...

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