Normalization and its various types in DBMS

Normalization and its types
Presented by:-
Shouvic Banik

DEFINITION
Normalization can be defined as :-
-A process of organizing the data in database to avoid data redundancy, insertion
anomaly, update anomaly & deletion anomaly.
-A process of organizing data into tables in such a way that the results of using
the database are always unambiguous and as intended. Such normalization is
intrinsic to relational database theory. It may have the effect of duplicating data
within the database and often results in the creation of additional tables.

Types of normalization:-
First Normal Form (1NF)
Second Normal Form (2NF)
Third Normal Form (3NF)
Boyce-Codd Normal Form (BCNF)
Fourth Normal Form (4NF)
Fifth Normal Form (5NF)

First Normal Form (1NF)
First normal form enforces these criteria:-
-Eliminate repeating groups in individual tables.
-Create a separate table for each set of related data.
-Identify each set of related data with a primary key

First Normal Form
This table is not in first normal form
because the “Color” column contains
multiple values.

After decomposing it into first normal form the
table looks like:-

Second Normal Form (2NF)
A table is said to be in 2NF if both the following conditions hold:
-Table is in 1NF (First normal farm)
-No non-prime attribute is dependent on the proper subset of any candidate key
of table(the table should not contain any partial dependency).
An attribute that is not part of any candidate key is known as non-prime
attribute.

Second Normal Form
-This table has a composite primary key i.e.,
customer id, store id. The nonprime attribute
is location. In this this case location depends
on Store_id, which is part of the primary key

After decomposing it into second normal form the
table looks like:-

Third Normal Form (3NF)
A table design is said to be in 3NF if both the following conditions hold:
-Table must be in 2NF
-Transitive functional dependency of non-prime attribute on any super key should
be removed
An attribute that is not part of any candidate key is known as non-prime attribute.
In other words, 3NF can be explained like this: A table is in 3NF if it is in 2NF
and for each functional dependency X-> Y at least one of the following conditions
hold:-
X is a super key of table
Y is a prime attribute of table
An attribute that is a part of one of the candidate keys is known as prime attribute.

Third Normal Form
In the table, book_id
determines genre_id and
genre_id determines genre
type. Therefore book_id
determines genre type via
genre_id and we have
transitive functional
dependency.

After decomposing it into third normal form the table
looks like:-

Boyce-Codd Normal Form (BCNF)
-It is an advance version of 3NF that's why it is also referred as 3.5NF. BCNF is
stricter than 3NF. A table complies with BCNF if it is in 3NF and for every
functional dependency X->Y, X should be the super key of the table.

Boyce-Codd Normal Form
>KEY: {Student, Course}
>Functional dependency
{student, course}->Teacher
Teacher-> Course
>Problem: teacher is not super key but
determines course.

After decomposing it into Boyce-Codd Normal form the
table looks like:-

Fourth normal form (4NF)
-Fourth normal form(4NF)is a level of database normalization where there
are no non-trivial multivalued dependencies other than a candidate key.
It builds on the first three normal forms (1NF, 2NF and 3NF) and the Boyce-
Codd Normal Form (BCNF). It states that, in addition to a database meeting the
requirements of BCNF, it must not contain more than one multivalued
dependency.

Fourth Normal Form
Key: {students, major, hobby}
MVD:->Major, hobby

After decomposing it into fourth normal form the
table looks like:-

Fifth Normal Form (5NF)
A database is said to be in 5NF, if and only if:
-Its in 4NF.
-If we can decompose table further to eliminate redundancy and anomaly, and
when we re-join the decomposed tables by means of candidate keys, we should
not be losing the original data, or any new record set should not arise.
In simple words, joining two or more decomposed table should not lose records
nor create new records.

Fifth Normal Form
Key: [seller company, product]
MVD: Seller ->Company, product
Product is related to company.

After decomposing it into fifth normal form the
table looks like:-

Normalization and its various types in DBMS

Normalization and its various types in DBMS

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Normalization and its various types in DBMS