Report (It) - Pangan
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Transcript of Report (It) - Pangan
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7/25/2019 Report (It) - Pangan
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Trivial andNon Trivial
Dependencie
s Reporter:Pangan, Carolina F.
III - 10
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Trivial Dependency
A dependency is triviali! it cannot possi"ly not"e satis#ed.
$ %&, P& ' -( %&
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)on Trivial
DependencyT*ey are t*e ones t*atcorresponds togen+ine integrityconstraints.
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Closure of A
Set ofDependencies
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%oe FDs ig*t iply
ot*ers:$ %&, P& ' -( $ CIT, T '
Iplies "ot* o! t*e !ollo/ing:
$ %&, P& ' -( CIT
$ %&, P& ' -( T
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Transitive F+nctionalDependency
Relvar R /it* t*ree attri"+tes A, andC.
A -( and -( C "ot* *old !or R
T*en it is easy to see t*at
A -( C also *olds !or R
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Arstrongs A2ios
1.Re3e2ivity
I! is a s+"set o! A, t*en A -(
.4.A+gentation
I! A -( , t*en AC -( C.
5.TransitivityI! A -( and -( C, t*en A -( C.
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6.%el!-deterination
A -( A
7.DecopositionI! A -( C, t*en A -( and A -( C
8.9nionI! A -( and A -( C, t*en A -( C
.CopositionI! A -( and C -( D, t*en AC -(
D.
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;eneral 9ni#cationT*eore
I! A -( and C -( D, t*en A 9 $ C < ' -( D
$=*ere 9 is +nion and - is seto! di>erence'
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Pro"le:
%+ppose /e are given relvar R /it*attri"+tes A, , C, D, ?, F and t*e
FDs:
A -( C
-( ?CD -( ?F
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A < eployee n+"er < departent n+"er
C < anagers eployee n+"er
D < pro@ect n+"er? < departent nae
F < percentage o! tie
AD -( F *olds !or R
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Ans/ers
1. A -( C $;IB?)'
4. A -( C $ D?CP%ITI) '
5. AD -( CD $ A9;?)TATI) '6. CD -( ?F $;IB?)'
7. AD -( ?F $ TRA)%ITIBIT '
8. AD -( F $ D?CP%ITI) '