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SQL Normalization SQL Server

Third Normal Form (3NF)

Byvivekjohari

Jan 26, 2010 #SQL Basic Concepts, #SQL Normalization
Third Normal Form (3NF) :- A table is said to be in the Third Normal form (3NF) if it satisfy the following conditions:-
1) It should be in the 2NF
2) It should not contain any transitive dependency which means that any non key column of the table should not be dependent on another non key column.

For example, let consider a table EmpProjDetails which contains the details about the employee and its project.

Table Name:-  EmpProjDetails
Primary Key: –  EmpId

EmpId      EmpName       EmpRegDate       Projectid        ProjectName
1                  Vivek               01/01/2006            1               Bankingexpress
2                  Neha                06/06/2007            2               BankingReport

Now, the table EmpProjDetails is in Second Normal Form (2NF), but it is not in the Third Normal Form because the non key column projectName is dependent on another non key column ProjectId. So to convert this table in the Third Normal Form, we need to decompose this table into the two tables EmpInfo and ProjInfo whose structure is given below:-

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Table Name:- EmpInfo
Primary Key: – EmpId

EmpId       EmpName          EmpRegDate         Projectid
1                  Vivek                   01/01/2006               1
2                  Neha                    06/06/2007               2

Table Name:- ProjInfo
Primary Key: – ProjectId

ProjectId          ProjectName
  1                   Bankingexpress
  2                   BankingReport

Now the above tables are in the Third Normal Form since they satisfy all the conditions for the Third Normal Form.

Related Aticles

Database Normalization
First Normal Form (1NF)
Second Normal Form (2NF)

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By vivekjohari

I am currently working as a Senior Database Professional and have around 18 years of experience in database. Degree:- Master Degree in Computer(MCA) Certification course in Data Science & Machine Learning from Indian Institute of Technology (IIT), Delhi Work experience:- Designing of the database. Database Optimization. Writing Complex Stored Procedures,Functions,Triggers etc. Designing and developing SSIS & DTS packages. Designing SQL Reports using SSRS. Database Server Maintenance. Certification:- MCTS: DA-100: Analysing Data with Microsoft Power BI MCTS: DP-300: Administering Relational Databases on Microsoft Azure Microsoft certified Sql DBA in Sql server 2008 (MCTS). Microsoft certified BI professional in Sql server 2008 (MCTS). Oracle certified profession DBA in ORACLE 10g (OCP) certified profession DBA in ORACLE 9i (OCP) My other publication Technical Blog:- Technologies with Vivek Johari Guest Author and Blogger at sqlservercentral.com

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46 thought on “Third Normal Form (3NF)”

  3. Thanks very well explained and in a very easy manner.Can you please explain 3.5NF,4NF,5NF,6Nf,7NF too with easy examples!!!!

    Reply

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