KM_Pres_PA_Ch5 update sp 08

KM_Pres_PA_Ch5 update sp 08 - Chapter 5 Starting To Put It...

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Chapter 5 – Starting To Put It All  Together Functional Dependency Normalization
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Functional Dependency The value of one attribute determines the value of another A function is (from math)      f(x) Mathematical definition: A function is a correspondence that exists between two  sets, X and Y, such that to each element x belonging to  set X there corresponds one and only one element y  belonging to set Y.  X is the independent variable and  Y is the dependent variable.
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Functional Dependency (cont ) Book's definition: An attribute B, is functionally dependent on another  attribute, A (or possibly a collection of attributes), if a  value for A determines a single value for B at any one  time. X functionally determines Y.  Written   X   Y  X functionally determines Y and Z  Written  X   Y, Z Note:  You must use the correct notation
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Does Pay Class FD Rate? REP- No LAST_ NAME FIRST _NAME STREET CITY ST ZIP COMMI SSION RATE Pay Class 20 Kaiser Valerie 624 Randall Grove FL 33321 20543 0.05 1 35 Hull Richard 532 Jackson Sheldon FL 33553 39216 0.07 2 65 Perez Juan 1626 Taylor Fillmore FL 33336 23487 0.05 1 Does Rate FD Pay Class? Does Rate FD Pay Class?
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The Venn Diagram Exercise Entity Name Value Value Entity Name Value Value
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Review of Keys:  Primary and Foreign Primary (a more precise definition) A minimal collection of columns (attributes) in a table on  which all columns are functionally dependent and that is  chosen as the main direct_access vehicle to individual rows Foreign Attribute (or attributes) in one relation which is a primary  key in a different relation.  The individual instances of the  foreign key must match to an individual instance of the  primary key in the other relation (or in special  circumstances be declared null).
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Question for Discussion What role does a Primary Key play in functional  dependency? How does this role help you understand what a  functional dependency is?
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Practice Exercise: FD The University registrar wants to record the following  information in a database.  Identify the functional  dependencies (FDs) that exist.  Use correct functional  dependency notation. Student number ( SSN ), student name ( Sname ), student's advisor number  ( Adv# ), student's advisor's name ( Aname ), student's advisor's office ( Advoff ),  student's advisor's phone ( Advph ), student's number of credits completed  ( Cred ), student status i.e., graduate or undergraduate ( Status ), and the classes  the student is currently enrolled in ( Course ), and the mid-semester grade  ( MS-grade ) for each of those classes.  An advisor has a single office which 
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This note was uploaded on 04/16/2008 for the course BA 105W taught by Professor Mohle during the Spring '08 term at CSU Fresno.

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KM_Pres_PA_Ch5 update sp 08 - Chapter 5 Starting To Put It...

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