How to Implement Second Normal Form

Posted in SQL | Normalization July 16, 2019
Tags: sql, database normalization, normal forms in database, second normal form
In this article I am going to explain how to Implement second normal form.
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Introduction

Normalization is used to organize the content of table. Normalization is a technique which eliminate redundancy and inconsistent dependency of data from database. Normalization makes database more flexible.

Basic Goal of normalization

  • Arrange data in database in to logical grouping.
  • Eliminate redundancy of data, it means minimizing the duplicate data in database.
  • Eliminate inconsistency of data 

Second Normal Form

 For a table in second normal from it must be in first normal form and every attribute is fully functionally dependent on entire primary key. Second normal form is used to remove redundant row data. 

Example

In this table data is in first normal form but not in second normal form. Here emp_id and project_number is combined primary key but you can find employee name by emp_id, project name by project number.  So we divide this table in more than one table.

Table in First Normal Form but not in Second Normal Form

emp_id Project_Number hour emp_name Project_Name Project_Location
D001  P0086 40 Vipendra  Metro Ticketing System  Delhi
D002  P0096 55  Deepak  Railway Ticketing System  Lucknow

Now we divide this table in three different tables and these tables are in second normal form.

Table 1

emp_id Project_Number hour
D001  P0086 40
D002  P0096 55

Table 2

emp_id emp_name
D001  Vipendra
D002  Deepak

 Table 3

Project_Number Project_Name Project_Location
 P0086  Metro Ticketing System  Delhi
 P0096  Railway Ticketing System  Lucknow

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