Gales biography resource center database normalization example

Normalization is a database design technique that reduces data redundancy and eliminates undesirable characteristics like Insertion, Update and Deletion Anomalies. Normalization rules divides larger tables into smaller tables and links them using relationships.

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The purpose of Normalization in SQL is to eliminate redundant repetitive data and ensure data is stored logically. The inventor of the relational model Edgar Codd proposed the theory of normalization of data with the introduction of the First Normal Form, and he continued to extend theory with Second and Third Normal Form. Later he joined Raymond F.

Boyce to develop the theory of Boyce-Codd Normal Form. For example, there are discussions even on 6 th Normal Form. However, in most practical applications, normalization achieves its best in 3 rd Normal Form. The evolution of Normalization in SQL theories is illustrated below-. Database Normalization Example can be easily understood with the help of a case study.

Assume, a video library maintains a database of movies rented out. Without any normalization in database, all information is stored in one table as shown below. Here you see Movies Rented column has multiple values.

In this comprehensive guide, we‘ll walk through the process of database normalization step-by-step.

An SQL KEY is a single column or combination of multiple columns used to uniquely identify rows or tuples in the table. SQL Key is used to identify duplicate information, and it also helps establish a relationship between multiple tables in the database. Note: Columns in a table that are NOT used to identify a record uniquely are called non-key columns.