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Ashraful Alam is a Software Architect, who has 8 years of professional experience in Software Development industry. This Bangladeshi national is involved with project management and development of several US based software projects from his country. Already he has managed and developed several software projects, which are being used by several users of different countries, such as USA, Canada, Australia, and Bangladesh. While developing and managing a team, he contains and maintains a set of well defined engineering practices developed by him and other online developer communities.

Due to his willingness to give effort to improve and share better software development practices, Ashraf has been awarded as “Most Valuable Professional” (MVP) in ASP.NET category by Microsoft since year 2007 multiple times, which is a rare honor and prestigious reorganization among the developers around the world.

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Functional Dependencies

The value of one attribute in a table is determined entirely by the value of another attribute.

For example, the birthday of a Customer can be determined by the primary key of the Customer, in which record the birthday belongs. Here an Customer’s birthday depends on the Customer’s primary key.

Customer birthday (depends on) -> Customer ID

The notation X -> Y means if and only if each X value is associated with at most one Y value.

We can find the birthday of a Customer, thru the ID of the Customer. Using the ID, for a one to one relationship (that is one Customer has ONLY one birthday), we can find the only birthday of a Customer. Where as using the birthday, we might find ID’s of several Customers, since same birthday might belong to multiple persons.

Understanding First Three Normal Forms

First normal form sample:

1. Create atomic values, i.e. which can’t be broken down more.

Address: Location + City + State + Country

Should be formed with separate fields:

Address table: Address ID, Location, City, State, and Country.

2. Remove repetitive column groups.

Customer table: Customer ID, Customer Name, Address ID, Address ID

Should be formed as:

Customer table: Customer ID, Customer Name

Customer Address table: Customer ID, Address ID

Second normal form sample:

Remove partial dependency.

Order Item table: Order ID, Inventory Item ID, Inventory Item Sell Price, Inventory Item Sell Quantity

Should be formed as:

Order Item table: Order ID, Inventory Item ID, Inventory Item Sell Quantity

Inventory Item table: Inventory Item ID, Inventory Item Sell Price

Third normal form sample:

Move the non-keys to a separate table, which don’t depend on keys (or depends on non-key).

Sales Order table: Sales Order No, Date, Customer No, Customer Name

Should be formed as:

Customer table: Customer No, Customer Name

Sales Order table: Sales Order No, Date, Customer No

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Posted on Wednesday, February 6, 2008 6:06 PM | Back to top


Comments on this post: Normalization Case Study and Theory

# re: Normalization Case Study and Theory
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i want to teach me about normalization
and frequently asked questions of the topic
Left by adisallem on Feb 16, 2009 12:35 AM

# re: Normalization Case Study and Theory
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i need some case study base on normlisation.
Left by nitin on Mar 05, 2009 5:59 PM

# re: Normalization Case Study and Theory
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sir i m mca student of pune university & i wnt slove case study on normalization up to 3 nf

pls help me !!!
Left by atul dubey on Apr 28, 2009 10:47 AM

# re: Normalization Case Study and Theory
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plz give me solved examples of normalization
Left by amber on Dec 02, 2009 4:07 AM

# re: Normalization Case Study and Theory
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sir plz give me solved example of normalization up to 3 nf but in tabler format
Left by komal on Dec 20, 2009 4:55 AM

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sir pls give me solved case study on normalization upto 3nf.
Left by Aarti on Apr 13, 2010 1:54 AM

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sir i m stdudent of mit.db offer to us. sir plz help me coz i m new in db and normaliztion is very difficult
Left by usman saeed on May 03, 2010 3:39 AM

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sir i am a student of miom i cant understand db its new for me plz normalization in tabuler form upto 3 nf send me thanks
Left by Asifhanif on Sep 18, 2010 11:24 PM

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sir i want solved case study of normalization up to 3nf
Left by vishranti gharge on Mar 24, 2011 6:14 PM

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