What is the process of database normalization in SQL server?

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We are just starting with SQL and we’ve been asked about normalizing our database. Can you walk us through what is meant by ‘database normalization’ and why it’s important?


The client needs a comprehensive explanation on the meaning, importance, and processes involved in ‘Database Normalization’ in an SQL server.

What is the process of database normalization in SQL server?

Database normalization is a critical process in designing and managing databases. It’s a systematic approach that seeks to minimize data redundancy and prevent issues such as update anomalies in databases.

Normalization involves breaking down a larger table into smaller, less redundant tables without losing any information. The purpose of Normalization is to eliminate unwanted redundancy and ensure data dependency i.e. data is logically stored.

Here is a step-by-step guide on database normalization using the standard guidelines or “normal forms”:

Step 1: 1NF (First Normal Form) – This ensures that every column in each table relates to the entity described by that table. Each attribute should have atomic values, meaning they cannot be broken down further. It makes sure all entries are unique within each set.

Step 2: 2NF (Second Normal Form) – Here, every nonprime attribute should be entirely dependent on every candidate key of the table.

Step 3: 3NF (Third Normal Form) – This eliminates transitive dependency from the relation. In simple terms, third normal form requires elimination of fields that do not directly depend upon the primary key – typically known as transitive dependencies.

Step4: BCNF (Boyce-Codd Normal Form) – Every determinant must be a candidate key

Step5: 4NF (Fourth Normal Form) – A table should not contain two or more independent multi-valued facts about an entity

There are also some advanced levels like

– The Elementarty Key Normal Form (EKNF)
– The Domain-Key Normal Form (DKNF)
– The 4th and 5th normal forms of elimination of multi-valued dependency.

But a well-normalized database should ideally at least be in the third normal form (3NF).

Why is Database Normalization important?

Normalization organizes your data to reduce redundancy and improve data integrity. When you have a normalized database, you don’t have to worry about inconsistencies or inaccuracies that could occur when changes happen. For example, without normalization, if an employee changes departments, the department name would need to be updated for each project they’re working on. If the update isn’t made in all the right places, the database becomes inconsistent. With normalization, updates are made in one place, removing this risk.

Is Normalization always required?

No. Database normalization is not always necessary especially when you deal with Small databases, Read-heavy workload systems or by situation where complex queries join many tables are common. Just remember that higher levels of normalization tend to increase joins and complexity and can impact database performance. You need to strike balance between careful design (normalization) and considerations for how database will be used.

Additional reading

  • For further insights regarding SQL database normalization stages from first through third – check out W3 Schools tutorials that covers these subjects extensively with excellent real world examples.

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