Database what is normalization

Create a personalised ads profile. Select personalised ads. Apply market research to generate audience insights. Measure content performance.

Develop and improve products. List of Partners vendors. Mike Chapple. Former Lifewire writer Mike Chapple is an IT professional with more than 10 years' experience cybersecurity and extensive knowledge of SQL and database management.

Updated on April 12, Tweet Share Email. Apps Best Apps Payment Services. Was this page helpful? Thanks for letting us know! Email Address Sign up There was an error. Please try again. You're in! Thanks for signing up. There was an error. Tell us why! More from Lifewire. In this example, the Title column is functionally dependent on Name and Date columns. These two keys form a composite key. In this case, it only depends on Name and partially dependent on the Date column.

Now, the course details are based on the entire key. We are not going to use a composite key. The third normal form states that you should eliminate fields in a table that do not depend on the key.

Consider the following example, in the table employee; empID determines the department ID of an employee, department ID determines the department name. Therefore, the department name column indirectly dependent on the empID column. So, it satisfies the transitive dependency. So this cannot be in third normal form. In computing, denormalization is the process of trying to improve the read performance of a database, at the expense of losing some write performance, by adding redundant copies of data or by grouping data.

Denormalization should not be confused with Unnormalized form. Database normalization is always a starting point for denormalization. Denormalization is a type of reverse engineering process that can apply to retrieve the data in the shortest time possible. Well, what happens if we add another email address column, another phone number? Database Normalization.

Table of Contents. Some Facts About Database Normalization. Database Normalization Rules. First Normal Form 1NF.

Second Normal Form 2NF.