Index Normalization and history of norm… Why we do normalization.. How many normal form.. (1NF) and (2NF) with example… (3NF) and (BCNF) with example.. Difference between 3NF and BCNF..--------------------------******----------------------

NormalizationNormalization is the process of removing

redundant data from tabels into improve storage efficiency and data integrity………

This process takes a relation schema through a series of tests to certify wether it satisfies a certain normal forms………..

History of normalization Edgar.F codd, the inventor of the relational

model,introduced the concept of normalization.. The first normal form(1NF)was proposed by

codd in 1970… Codd went on to define second normal

form(2NF) and third normal form (3NF) in 1971.To eliminate some anomalies in (3NF) the

stronger version of 3NF is called“BCNF” was proposed by “Boyce and Codd”…

Why we do normalization? It is the process of analyzing the given

relation schema based on their functional dependencies and primary keys to achieve the disiarable properties of.

It is used to minimizing data redundancy. It is used to minimizing deletion,insertion and

updation anomalies.

Sid. s.name c.id c.name f.id f.Name

S1 A C1 C F1 X

S2 A C1 C F1 X

S3 A C1 C F1 X

S4 B C2 C++ F2 Y

S.id s.name c.id

S1 A C1

S2 A C1

S3 A C1

s4 B C2

c.id c.name f.id f.name

C1 C F1 X

C2 C++ F2 Y

R

R1 R2

Lossless=R1∩R2≠ᶲ shoulb be superkey either R1 and R2.. Dependency preserve…

How Many normal form? Initially codd proposed three normal form,

which he called first,second and third normal forms.

A stronger defination of third normal form is called Boyce-codd normal form(BCNF),was proposed later by Boyce-Codd.

Later fourth and fifth normal form were proposed.

First normal form. A Relation schema R is in 1NF if the domain of

all attributes of R is atomic…. A Domain is atomic if element of the domain

are considered to be indivitual units….All value for a given attribute must be of the

same type…. compound attribute is not allowed in first

normal form….Each attribute name must be unique ….. What is atomic value?

Person Id Name Phone num.1 Rajat 7489

90547645

2 Megha 9032

Person Id Phone num. Name

1 7489 Rajat

1 9054 Rajat

1 7645 Rajat

2 9032 Megha

person

student

Multivalued attribute is not allowed in first normal form…….

Person id Name

1 Rajat

2 Megha

………… ………

………. ……….

Person id Phone num.

1 7489

1 9054

1 7645

2 9032

P1

P2

Second normal form Second normal form (2NF) is a normal form

used in database normalization. 2NF was originally organised by E.F.CODD. A table that is in first normal form(1NF) must

meet additional criteria if it is two qualify for second normal form.

Second normal forms state that it should meet all the rules for 1NF and their must be no partial dependences of any of the coloumns on the primary key.

What is partial dependency

St.ID Batch Id

Name Phn num.

email Batch time

Start date

Batch size

faculty

1 b1 amit 7489-- amit4@-----

4:30pm 6.05.16 20 Rajat

2 b1 amit ----- ----- ----- ----- ----- -----

3 b2 rajat ----- ----- ----- ----- ----- -----

4 b2 raman ----- ----- ----- ----- ----- -----

Student

S.Id name email Phn.1 amit amit4

@7489

2 amit ------- -------

3 ------- ------ ------4 ------ ------ -------

B .Id B.tym s.d b.size

b1 4:30p 6.05.16 20

b1 -------- -------- -------

b2 ------- --------- -------

b2 ------- -------- --------

S.Id B.id s.d

1 b1 6.05.2016

2 b1 7.05.2016

3 b2 6.05.2016

4 b2 -------------

Student Batch

Student Batch

Third normal forms

Third normal forms(3NF) is a normal form used in database normalization.

(3NF) was originally defined by E.F.CODD…

Third normal form…• Codd’s defination states that a table is in 3NF if and

only if both of the following condition should be hold.

(i) the relation R (table) is in (2NF)…. (ii) every non prime key attribute of R(Table)

is non –transitively dependent on non -prime key attribute of R…..

(i.e.)no transitive dependencies….

Rollno. Name Dept. Year Hostel nm.

10 Rajat Physics 1 H1

20 Raman Math 1 H1

30 Rahul Cs. 2 H2

40 Akash IT Dept. 2 H2

50 Megha Commerce 3 H3

Student info.

Roll no. Name Dept. Year

10 Rajat Physics 1

20 Raman Math 1

30 Rahul Cs. 2

40 Akash IT Dept. 2

50 Megha Commerce 3

Year Hostel nm.1 H11 H12 H22 H23 H3

Student

Hostel

Boyce codd normal form

The official qualification for BCNF are:-• A table is already in 3NF.• Atmost one determinant must be superkey in

relation..

Atmost one determinant that are not superkeys are removed to place in another table.

The difference between 3NF and BCNF

The difference between 3NF and BCNF is that for a functional dependency A->B ,3NF allows this dependency in a relation if A is prime key attribute and B is not a cnadidate key..

Whereas BCNF insists that for this dependency to remain in a relation B,must be a candidate.

Table Faculty Faculty id Name Dept Dept head

101 Rajat agrawal Computer sc…. Mrs. pavani..

102 Akash agrawal Mathematics Kiran avasthi

103 R.Gupta physics D.K.Ranjak

----- ------ ------- ------

Faculty id->Dept, Dept->Depthead Faculty id->Depthead

Faculty Id Name Dept

101 Rajat agrawal Computer sc.

102 Akash agrawal Mathematics

103 R.gupta Physics

104 -------- ---------

Dept Depthead

Computer sc. Mrs.pavani..

Mathematics Kiran Avasthi

Physics R.K.Ranjak

---------- -------------

Faculty

Department