Transcript S0

Deanship of Distance Learning
Avicenna Center for E-Learning
Database Normalization
Prepared by:
Dr. Samir Tartir
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Definition
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Normalization is the process of removing
redundant data from your tables in order to
improve:
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storage efficiency
data integrity
scalability
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Goals
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Eliminating redundant data
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For example, storing the same data in more than
one table)
Ensuring data dependencies make sense
Avicenna Center for E-Learning
Motivation
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Minimize data redundancy
To make database structure flexible
Data should be consistent throughout the
database
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Insert Anomaly (explained later)
Update Anomaly
Deletion Anomaly
Complex queries required by the user should
be easy to handle.
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Advantages
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More efficient data structure.
Avoid redundant fields or columns.
More flexible data structure i.e. we should be
able to add new rows and data values easily
Better understanding of data.
Ensures that distinct tables exist when
necessary.
Close modeling of real world entities, processes
and their relationships.
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Disadvantages
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You cannot start building the database before
you know what the user needs.
Normalizing the relations to higher normal
forms i.e. 4NF, 5NF the performance
degrades.
It is very time consuming and difficult process
in normalizing relations of higher degree.
Careless decomposition may leads to bad
design of database which may leads to
serious problems.
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What is a Normal Form?
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A set of conditions that data must satisfy
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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)
Sixth Normal form (6NF)
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