Notes and Study Materials

Normalization and Its Need

 

 

Normalization is a process for evaluating and correcting table structures to minimize data redundancies, thereby reducing the likelihood of data anomalies. The normalization process involves assigning attributes to tables based on the concept of determination.

Normalization works through a series of stages called normal forms. The first three stages are described as first normal form (1NF), second normal form (2NF), and third normal form (3NF). From a structural point of view, 2NF is better than 1NF, and 3NF is better than 2NF. For most purposes in business database design, 3NF is as high as you need to go in the normalization process. Properly designed 3NF structures also meet the requirements of 4th normal form (4NF).

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1st Normal Form
2nd Normal Form
3rd Normal Form

 

The Need for Normalization

 


There are two common situations in which database designers use normalization.
 
• When designing a new database structure based on the business requirements of the end users, the database designer will construct a data model using a technique such as Crow’s Foot notation ERDs. After the initial design is complete, the designer can use normalization to analyze the relationships that exist among the attributes within each entity, to determine if the structure can be improved through normalization.

• Alternatively, database designers are often asked to modify existing data structures that can be in the form of flat files, spreadsheets, or older database structures. Again, through an analysis of the relationships among the attributes or fields in the data structure, the database designer can use the normalization process to improve the existing data structure to create an appropriate database design.

 

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BCNF

4th Normal Form

Denormalization