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Normalization in sql

Rajat vats

BCA, School of Ccomputer Application

Lovely Professional University,Jalandhar

I. INTRODUCTION (NORMALIZATION IN SQL)

Normalization is the process of restructuring the logical data

model of a database to eliminate redundancy, organize dataefficiently and reduce repeating data and to reduce the potential

for anomalies during data operations.

Data normalization also may improve data consistency and

simplify future extension of the logical data model.The formal classifications used for describing a relational

database's level of normalization are called normal forms .

I. WHAT HAPPENS WITHOUT NORMALIZATION?

A non-normalized database may store data

representing a particular referent in multiple locations.

An update to such data in some but not all of thoselocations results in an update anomaly, yielding

inconsistent data. A normalized database preventssuch an anomaly by storing such data in only one

location.

Similarly, such dependencies in non-normalized

databases can hinder deletion. That is, deleting data

from such databases may require deleting data fromthe inappropriate dependency. A normalized database

prevents such deletion anomalies by ensuring that allrecords are uniquely identifiable and contain no

extraneous information.

It can creates error .

II. FORMS IN NORMALIZATION IN SQL.

Normal Forms:

The first normal form requires that tables be

made up of a primary key and a number of atomic fields, andthe second and third deal with the relationship of non-key

fields to the primary key.

These have been summarized as requiring that all non-key

fields be dependent on the key, the whole key and nothing butthe key.

First Normal Form

First normal form lays the groundwork for an organized

database design: Ensure that each table has a primary key:minimal set of attributes which can uniquely identify a record

Second Normal Form

Second normal form If a table has a composite key, allattributes must be related to the whole key:

The database must meet all the requirements of the first normalform

Third Normal Form

Third normal form requires that data stored in a table be

dependent only on the primary key, and not on any other fieldin the table. The database must meet all the requirements of thesecond normal form.

Boyce-Codd Normal Form

Boyce-Codd normal form requires that there be no non-trivial

functional dependencies of attributes on something other than asuperset of a candidate key (called a superkey)

Fifth Normal Form

Fifth normal form requires that there are no non-trivial joindependencies that do not follow from the key constraints. A

table is said to be in the 5NF if and only if it is in 4NF andevery join dependency in it is implied by the candidate keys.

Sixth Normal Form

This normal form was, as of 2005, only recently proposed: thesixth normal form was only defined when extending the

relational model to take into account the temporal dimension .

Unfortunately, most current SQL technologies as of 2005

do not take into account this work, and most temporalextensions to SQL are not relational.

II.NORMALIZATIONINSQLFIGURE

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III. ADVANTAGESOFNORMALIZATIONINSQL

The main advantage of normalisation is that it helps toreduce redundancy..

Normalization increase granularity and Granularity is the

scope of a definition for any particular thing.

maintain data intergrity, and make the data model as simpleas possible.

Expandability: normalized data are less diskspace usage,better maintainability and expandability and betterperformances.

Local autonomy: The normalization is brought nearer to

its users. This can effect a cultural change as it allowspotentially greater control over local data .

A. Disadvantages:

a. Architectural complexity.

b. Cost.

c. Security.

d. Reduced Efficiency

e. Strucutural Disadvantages

f. Lack of experience.

g. Database design more complex.

A.

IV. ACKNOWLEDGMENT

I sincerely thank to my project guide Mrs Supreet Thapar,School of Computer Application Lovely Professional

University, Punjab for guidance and encouragement in carryingout this project work I also wish to express my gratitude to the

my seniors and colleagues who rendered their help during theperiod of my project work. I wish to avail myself of this

opportunity, express a sense of gratitude and love to my friendsand my beloved parents for their manual support, strength, help

and for everything

Place: Jalandhar

V. REFERENCES

a. Google

b. Wikipedia

c. Database pdf

d. Power point presentation

e. Teachers help

f. Teacher notes

g. Senior helps

.