Rules of data normalisation, Database Management System

Rules Of Data Normalisation

 Let us now summarise Normalisation with the help of various clean rules. The following are the necessary rules for the Normalisation process:

1.   Eliminate Repeating Groups: Make an individual relation for each set of related attributes, and give every relation a primary key.

2.   Eliminate Redundant Data: If an attribute relies on only part of a multi- attribute key, remove it to an individual relation.

3.   Eliminate Columns Not Dependent On Key: If attributes do not give to a description of the key, remove them to a individual relation.

4.   Isolate Independent Multiple Relationships: No relation may have two or more 1:n or n:m relationships that are not directly linked.

5.   Isolate Semantically Related Multiple Relationships: There may be practical constrains on information that give explanation for separating logically related many-to-many relationships.

Let's define these steps of Normalisation through an instance:

 Let us make a file of all the employees in the company. In the original employee file, every employee name is pursued by any databases that the member has experience with. Some may know many, and others may not know any.





Department- Loc








Faisal Khan





Manisha Kukreja





Sameer Singh

DB2, Oracle



Posted Date: 3/7/2013 2:25:30 AM | Location : United States

Related Discussions:- Rules of data normalisation, Assignment Help, Ask Question on Rules of data normalisation, Get Answer, Expert's Help, Rules of data normalisation Discussions

Write discussion on Rules of data normalisation
Your posts are moderated
Related Questions
Consider the subsequent relations RENTER(rno, fname, lname, address, tel_no, pref_type, max_rent) VIEWING(rno, pno, date, comment) PROPERTY_FOR_RENT( pno, street, area ,city,

Give the general form of SQL query? Select  A1, A2............., An From  R1, R2..............., Rm Where  P

A file manipulation command that extracts some of the records from a file is called ? A file manipulation command that extracts some of the records from a file is called SELECT

What are called multilevel indices? Indices with two or more levels are known as multilevel indices.

How much would you charge to create a database encompassing an Online Bakery with all the elements below? I. Describe the application that you would like to design. This should

Normalize the given relation to 3NF, justifying each step

DDL Compiler The DDL compiler changes the data definition statements (such as CREATE TABLE .... in SQL) into a set of tables having metadata tables. These tables have infor

With the linear commit protocol, sites are connected in a chain, and the subtransaction at the left-hand end of the chain initiates the protocol. Propose a crash recovery protocol

What are stored and derived attributes? Stored attributes: The attributes keeps in a data base are known as stored attributes. Derived attributes: The attributes that are de