Answer / vikram

The task of a database designer is to structure the data in
a way that eliminates unnecessary duplication and provides a
rapid search path to all necessary information. The process
of refining tables, keys, columns, and relationships to
create an efficient database is called normalization

because there is no redundant, neglected data and normalized
tables produce rapid, efficient joins.

There are 5 different normalization methods.

First Normal Form (1NF): Each field in a table must contain
different information.

Second Normal Form (2NF): All attributes that are not
dependent upon the primary key in a database table must be
eliminated.

Third Normal Form (3NF): No duplicate information is
permitted. So, for example, if two tables both require a
common field, this common field information should be
separated into a different table.

There are 2 more normalization forms, fourth normal form
(4NF) and fifth normal form (5NF), but they are rarely used.
Normalization makes databases more efficient and easier to
maintain.

Answer / kumaresan chandran

Normalization:
Normalization is the process of designing a data
model to efficiently store data in a database. The end
result is that redundant data is eliminated, and only data
related to the attribute is stored within the table.

First normal form (1NF):
An entity type is in 1NF when it contains no repeating
groups of data.

Second normal form (2NF):
An entity type is in 2NF when it is in 1NF and when all of
its non-key attributes are fully dependent on its primary key.

Third normal form (3NF):
An entity type is in 3NF when it is in 2NF and when all of
its attributes are directly dependent on the primary key.

Answer / a.mohan kumar

To avoid redundancy and to constructing an efficient
database we use normalization.its a concept which is used to
construct efficient database .the types of normalization are:
First Normal form (1NF): A relation is said to be in 1NF if
it has only single valued attributes, neither repeating nor
arrays are permitted.

Second Normal Form (2NF): A relation is said to be in 2NF if
it is in 1NF and every non key attribute is fully functional
dependent on the primary
key.

Third Normal Form (3NF): We say that a relation is in 3NF if
it is in 2NF and has no transitive dependencies.

Boyce-Codd Normal Form (BCNF): A relation is said to be in
BCNF if and only if every determinant in the relation is a
candidate key.

Fourth Normal Form (4NF): A relation is said to be in 4NF if
it is in BCNF and contains no multi valued attributes.

Fifth Normal Form (5NF): A relation is said to be in 5NF if
and only if every join dependency in relation is implied by
the candidate keys of relation.

Domain-Key Normal Form (DKNF): We say that a relation is in
DKNF if it is free of all modification anomalies. Insertion,
Deletion, and update anomalies come under modification
anomalies.
om Namasivaya.

Answer / subhash vandewar

Normalizatiin is the scientific method of breaking down
complex table sturcture into simple table structure by
using certain rules.using this method you can reduce
redundency in a table and eliminate the problem of
inconsisteny and disk space usage.

First Normal Form(1NF):
a table is said to be in first normal form when each
cell of the table prcisely contain one value.

Second Normal Form (2NF):
a table is said to be in second normal form when it is
in 1NF and every attribute in the row in functionaly
dependent upon whole key and not just a part of key.
Third Normal Form (3NF):
a table is said to be in second normal form when it is 2NF
and every non key attribute is functionaly dependent only
on the primary key.

Answer / abc

1
2
3

Answer / md moinuddin

1NF: If any tables have a many to many relationship this must be broken out using a JOIN table. For example, Customers can have many Suppliers and Suppliers can supply to many Customers. This is known as a many to many relationship. You would need to create a JOIN table that would have a primary key made up of a foreign key reference to the Customers table and a foreign key reference to the suppliers table. Therefore the SuppliersPerCustomer table would be {SupplierID, CustomerID}. Now the Suppliers table will have a 1 to many relationship with the SuppliersPerCustomer table and the Customers table will also have a 1 to many relationship with the SuppliersPerCustomer table.

2NF: The database must meet all the requirements of the 1NF.

In addition, records should not depend on anything other than a table's primary key (a primary key can be made up of more than one field, only if absolutely necessary like in a JOIN table).

Example:

A customers address is needed by the Customers table, but also by the Orders, and Invoices tables. Instead of storing the customer's address as a separate entry in each of these tables, store it in one place, either in the Customers table or in a separate Addresses table.

3NF : The database must meet all the requirements of the 1NF and 2NF.


A relational table is in third normal form (3NF) if it is already in 2NF and every non-key column is non transitively dependent upon its primary key.

The Customer table contains information such as address, city, postcode imagine it also contained a column called shipping cost. The value of shipping cost changes in relation to which city the products are being delivered to, and therefore is not directly dependent on the customer even though the cost might not change per customer, but it is dependent on the city that the customer is in. Therefore we would need to create another separate table to hold the information about cities and shipping costs.

Answer / dan stufflebeam

There are actually up to 7th Normal Forms (but anyone who
goes beyond 4th or 5th is insane.

6th NF: http://en.wikipedia.org/wiki/Sixth_normal_form

7th NF:
http://wedonotuse.blogspot.com/2005/11/ukoug-scotland-tuomas-7th-nf.html

Answer / nitesh vedant

Normalization is a sort data of long data. Genarally it
has three forms. (1) 1st. normal form, (2)2nd normal form
and (3) 3rd normal form.
After complete this three types normalization is made.

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