Normalization of Database Tables Day 4

Normalization of Database Tables Day 4 -...

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  vjk - Database Technologies  Normalization of Database  Tables
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  vjk - Database Technologies  Objectives After completing this lesson you should  be able to understand the following: What normalization is and what role it  plays in database design? About the normal forms 1NF, 2NF, 3NF,  BCNF, and 4NF 
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  vjk - Database Technologies  Continued… How normal forms can be transformed from  lower normal forms to higher normal forms? That normalization and E-R modeling are  used concurrently to produce a good  database design That some situations require denormalization  to generate information efficiently
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  vjk - Database Technologies  Table is basic building block in  database design Normalization is process for assigning  attributes to entities Reduces data redundancies Helps eliminate data anomalies Produces controlled redundancies to link  tables
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  vjk - Database Technologies  Keys A key helps define entity relationships. • The key ’s role is based on a concept known as determination , which is used in the definition of functional dependence . – The attribute B is functionally dependent on A if A determines B. – An attribute that is part of a key is known as a key attribute . – A multi-attribute key is known as a composite key . If the attribute (B) is functionally dependent on a composite key (A) but not on any subset of that composite key , the attribute (B) is fully functionally dependent on (A).
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  vjk - Database Technologies  Database Tables and  Normalization Normalization  is a process for assigning  attributes to entities. It reduces data  redundancies and helps eliminate the data  anomalies.  Normalization works through a series of stages  called normal forms: First normal form (1NF) Second normal form (2NF) Third normal form (3NF) Fourth normal form (4NF) The highest level of normalization is not always  desirable.
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  vjk - Database Technologies  Some basic terms functional dependency denoted by X Y,  between two sets of attributes X and Y that  are subsets of the attributes of relation R,  specifies that the values in a tuple  corresponding to the attributes in Y are  uniquely determined by the values  corresponding to the attributes in X. 
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  vjk - Database Technologies  the social security number uniquely  determines a name; SSN Name
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  vjk - Database Technologies  Dependencies All key attributes must be dependent on the    Primary Key (PK) If the PK is a composite PK and an attribute    is dependent on only a part of the composite    PK, a  partial dependency  exists   If an attribute is dependent on a non-key attribute,  it exhibits a  transitive dependency
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This note was uploaded on 07/15/2011 for the course ECO 2023 taught by Professor Mr.raza during the Summer '10 term at FAU.

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Normalization of Database Tables Day 4 -...

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