15856 Normalization

7/26/2019 15856 Normalization

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NORMALIZATION


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Objective of Normalization

To free relations from undesirableinsertion ,deletion,update anomalies.

To remove inconsistencies Normalization of data can be dened

as a process durin! "#ic# redundantrelation sc#emas are decomposed b$

brea%in! up t#eir attributes into smallerrelation sc#emas t#at possess desirableproperties.


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A relation is said to be in particular normalform if it satises a certain specied set ofconstraints.&or '!(

)N&( eliminate repeatin! !roups

*N&( Non+%e$ attribute full$ functionaldependence on -

N&( 'liminate Transitive dependenc$ on

- /N&( remove Multivalue dependenc$

0N&( 1oin 2ependenc$


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)stNormal &orm

A relation is said to be in )stnormal formif 3 onl$ if ever$ entr$ of t#e relation #asatmost a sin!le value.

Faculty Name Course_code

#aris# 45'6)45')745'06)

ardeep 45'6*45')745')6)

RA1 45'/6*45')6)


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To ma%e it in )N&,"e #ave to useatomic value(

Faculy_name Course_code

8aris#8aris#8aris#

45'6)45')745'06)

ardeepardeepardeep

45'6*45')745')6)

RajRaj

45'/6*45')6)


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*nd Normal form

A relation is said to be in *ndNormal formif(

).If it in )N&*.All its non+primar$ attributes are full$

dependent on t#e primar$ %e$.


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4onsider relation Lab9course

Lab_course Teacher Lab_no Lab_capacity

45'6) ANIL +6) 6

45'6/ AMIT +6* *:

45')7 5;MIT +6 *

45')6) NI-8IL +6/ 6

45'06) RA8;L +60 *:


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&irst nd out all t#e functionaldependencies (

). Lab9course Teac#er

*.Lab9course Lab9no

.Lab9course

Lab9capacit$

) 3 * dependencies e


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To ma%e it in *N&,decompose itinto t"o relations

Lab9course teac#er

Lab9course Lab9no

Lab_course Teacher Lab_no

45'6) ANIL +6)

45'6/ AMIT +6*

45')7 5;MIT +6

45')6) NI-8IL +6/

45'06) RA8;L +60


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Lab9noLab9capacit$

Lab_no Lab_capacity

+6) 6

+6* *:

+6 *

+6/ 6

+60 *:

Now these two relations are in 2NF becoz in each

relation allthe non primary attributes are fully functional onprimary key


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rdNormal form

A relation is in rdnormal form(

If it is in *N&

All non+primar$ attributes #ave notransitivit$ dependenc$ on t#e primar$%e$


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4onsider student relation(

rollno Game Fee

) 4ric%et *66

* Tennis 66

&ootball )66

/ 4ric%et *66

0 8oc%e$ )06

This relation is in NFbecoz all its attribute contain ato"lso it is in 2NF becoz all its non#primary key attributefunctional dependent on the primary key $%ollNo&'(ut it is not )NF becoz there is transiti!e dependency'

%ollno*amefee


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5o Anomalies e


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=o$ce 4odd Normal form

=4N& is an improved form of N&.

A relation is in N& ,if ever$ determinant is acandidate %e$

A determinant is an attribute on "#ic#ot#er attribute is full$ functional dependent.

'!(

Re!istrationNo,sectionNocourse9name

5ectionNo ,course9I2facult$9name


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/t#Normal &orm

A relation is in /t#N&(

If it is in rdN& OR =4N&

If it contains no multi valueddependencies. OR t#ere are multi valuedependencies but t#e attributes "#ic#are multi value dependent on a specic

attribute are dependent bet"eent#emselves.

4 id ' l R l ti


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4onsider 'mplo$ee Relation(case)(

,mp_id Lan*ua*e +kill

)6) 'n!lis# Teac#in!

)6) 8indi 5in!in!

)6) unjabi 4onversation

*6* 'n!lis# 5in!in!

*6* 8indi teac#in!

8ere bot# emplo$ees %no" more t#an one lan!ua!e 3 also #aveMore t#an one s%ill.t#us multivalued dependenc$ eer from an$ anomal$.


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relation "it# multi value

dependencies(

,mp_id Lan*ua*e +kill

)6) 'n!lis# Teac#in!

)6) 8indi 4onversation

)6) 'n!lis# 4onversation

)6) 8indi Teac#in!

*6* 'n!lis# 5in!in!

*6* 8indi teac#in!

8ere bot# emplo$ees %no" more t#an one lan!ua!e 3 also #aveMore t#an one s%ill.t#us multivalued dependenc$ eer5 from 2'L'T' 3 ;2AT' anomal$.


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To ma%e it into /N&,decompose itinto t"o smaller tables 3 it "ill

not su>er from anomal$,mp_lan*ua*e,mp_id lan*ua*e

)6) 'n!lis#

)6) 8indi

*6* 'n!lis#

*6* #indi

,mp_skill,mp_id skill

)6) Teac#in!

)6) 4onversation

*6* 5in!in!

*6* teac#in!


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0t#Normal &orm

A relation is said to be in 0t#N& if(

It is in /N&

It can not be furt#er non+lossdecomposed.


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4onsider t#e table

"*ent Company .roduct_name

5uneet A=4 N;T

5uneet A=4 5cre"

5uneet 42' =olt

Raj A=4 bolt

T#is table is in /N& becoz it contains no multi+valued dependebut contain a redundanc$ as 5uneet is a!ent for A=4 t"ice 3t#ere is no "a$ of eliminatin! t#is redundanc$ "it#out inform


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2ecomposin! table into p)3p*

"*ent Company

5uneet A=4

5uneet 42'

Raj A=4

"G,NT .%/01CT_name

5uneet Nut

5uneet 5cre"

5uneet =olt

Raj bolt

No" redundanc$ #as been eliminated but t#e information about "#icMa%e "#ic# products 3 "#ic# of t#ese products t#et suppl$ to "#ic# a#as been lost.


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resultant table is as follo"s

named as A!entNe"(


5uneet A=4 Nut

5uneet A=4 5cre"

5uneet A=4 =olt?

suneet 42' Nut?

suneet 42' 5cre"?

suneet 42' bolt

raj A=4 bolt

T#e resultin! table after join is spurious as asteris%ed ro" of tacontains incorrect information.

N id t bl i


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No" consider table isdecomposed into parts ),*3

Company .roduct_name

A=4 Nut

A=4 scre"A=4 bolt

42' bolt


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No" perform join on A!entNe" 3


suneet A=4 nut

suneet A=4 scre"

suneet A=4 =olt?

suneet 42' bolt

raj A=4 bolt

T#is still contain spurious ro"5o it is not possible to decompose A!ent table "it#out losin! information

And it #as to be accepted t#at it is not possible to eliminate all redundasin! normalization becoz it can not be assumed t#at all decompositions "i

15856 Normalization

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