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Difference Between 1NF and 3NF in DBMS

DBMS | First Normal Form (1NF) Vs. Third Normal Form (3NF): In this tutorial, we will learn about the first and third normal forms (1NF and 3NF), and the differences between 1NF and 3NF with the help of examples. By IncludeHelp Last updated : May 29, 2023

What is First Normal Form (1NF)?

An object that does not have any repeated columns or data classes can be termed as the First Norm. 1NF is the First normal form, which includes the minimum set of criteria for normalizing a relational database. A table conforming to 1NF guarantees that it truly reflects a relationship i.e. it does not contain any repeated records), but for 1NF there is no widely agreed meaning. A significant property is that no attributes that are relationally valued, i.e. all attributes should have atomic values, should be included in a table that complies with 1NF.

First Normal Form (1NF) Example

101 Ram 8877665544 MP
102 Rex 8574783832 Maharashtra
103 Kapil 7390372389 Delhi

From the above-mentioned student database table, it is depicting that there is not any multivalued or composite attribute. Thus the given table is in first normal form (1NF).

What is Third Normal Form (3NF)?

If the table/entity is already in the second normal form and the table/entity columns are non-transitively based on the primary key, it means that a table is considered in the third normal form.

If a transitive dependence occurs, by putting the attribute(s) in a new relationship along with a copy of the determinant, we delete the transitively based attribute(s) from the relation. Most of the 3NF tables are free of addition, modification, and deletion anomalies. To decrease data replication and to achieve data integrity, 3NF is used.

Third Normal Form (3NF) Example

onsider relation R (A, B, C, D, E)

A -> BC,
CD -> E,
B -> D,
E -> A

All viable candidate keys in the above relationship are {E, B, CD, BC} and all attributes are main on the right side of all functional dependencies.

What are the differences between 1NF and 3NF in DBMS?

Since both 1NF and 3NF are the normalization forms in the database management system still they have differences. The following are the main differences between 1NF and 3NF normalization forms:

1 There is no composite attributes in 1 NF. There is no transitive functional dependency in 3NF.
2 Any relation must be atomic in order to be in 1NF and should not contain any composite or multi-valued attributes. There should be no transitive dependence in order to be in 3NF, which is not a non-prime attribute that should depend transitively on the candidate key.
3 For the first normal form, functional dependency is not required. The functional dependencies in 3NF are already present in 1NF and 2NF.
4 1NF is less effective than 3NF. 3NF is stronger than 1NF.
5 1NF contains candidate keys which comply with 2NF automatically. The 3NF form will require a table that is in the 2NF or 1NF to be decomposed.
6 Duplicate columns are deleted from the same table. This removes columns that do not rely on the primary key.

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