Friday, December 27, 2013

Normalization

NORMALIZATION Good selective informationbase mark must be matched to dear evade structures. -TABLE is the basic building block in the entropybase tendency bidding -ER modeling yields good delay structure, yet it is presumable to create a poor add-in structure. -Solution? NORMALIZATION NORMALIZATION address -of efficiently organizing data in a database -for evaluating and correcting tabulate structures to denigration data redundancies, thereby reducing data anomalies. two goals: -eliminating redundant data (ex.: storing the same data in more than than title-holder table) -ensuring data dependencies make sense ( entirely storing related data in a table). Stages of Normalization Normal Form interpretation 1NF Table format, no repeating groups and PK identified 2NF 1NF and no partial dependencies 3NF 2NF and no transitive dependencies BCNF Every determinant is a prognosis key (special cause of 3NF) 4NF 3NF and no independent multiva lued dependencies Why do we normalize? -Avoiding nulls on Primary key -Eliminating data unlikeness -Removing data redundancies which yields to data anomalies Normalization service Objective ? bring on tables that have the ff.
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characteristics: oEach table represents a single subject oNo data pointedness will be unnecessarily stored in more than integrity table ? ensure data are updated in only whiz place oAll attributes in a table are dependent on the primary key tabular Representation. DRAG Software Solutions has the following projects where employees are assigned to one or more projects, each employee has their corresponding job smorg! asbord with the hours spent in every project. ProjNumProjNameEmpNumEmpNameJobClassChgPerHrHrsSpent hundred and oneElection mechanization100Gorio ArecibSystems Analyst50045 101Kird TuddaoProgrammer cd40 104Ritch AnevaInterface Designer39045 105Riki MaribbayEvaluator30035 103 patient of study System100Gorio ArecibSys Analyst50050 101Kird TuddaoProgrammer40040...If you want to get a abundant essay, order it on our website: BestEssayCheap.com

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