First Normal Form (1NF)

If a table in the database is not properly normalized and if it has redundancy then the table will not only consume extra memory in your database but also it will be difficult to handle and update the database. Insert, Update and delete are the most common anomalies if a database is not properly normalized.

This is where normalization of data comes into use.

There are different levels of normalization.

normal forms
  1. First Normal Form -- 1NF
  2. Second Normal Form -- 2NF
  3. Third Normal Form -- 3NF
  4. Boyce Codd Normal Form -- BCNF
  5. Fourth Normal Form -- 4NF
  6. Fifth Normal Form -- 5NF

In this tutorial we will be discussing about the First Normal Form(1NF).

First Normal Form (1NF)

A relation is said to be in first normal form, if it does not contain a composite attribute or a multi-valued attribute (or) if a relation contains composite attribute or a multi-valued attribute, then it violates first normal form (1NF). Also every attribute in that relation must be a single valued attribute.

Rules for First Normal Form -- 1NF

  • It must contain only single valued attributes.
  • Domain of the attribute does not change.
  • There must be a unique name for every attribute (or) column.
  • The order in which the data is stored doesn’t matters.

Let’s consider the following example:

The relation Employee in the first table is not in first normal form (1NF) because, it contains a multi-valued attribute Emp_Phn.

First normal form table

Now let’s convert the table into 1NF by decomposition.

First normal form
  • There are only Single Valued Attributes.
  • Attribute Domain does not change.
  • There is a Unique name for every Attribute/Column.
  • The order in which data is stored, does not matter.

Now the table is in first normal form (1NF).

Also Read: --> Views in SQL -->DBMS Integrity Constraints

Reference: Database Management Systems

First Normal Form in DBMS | 1NF with example | Normalization in dbms

FAQ?

What is First Normal Form?

A relation is said to be in first normal form, if it does not contain a composite attribute or a multi-valued attribute (or) if a relation contains composite attribute or a multi-valued attribute, then it violates first normal form (1NF).

Rules for 1NF ?

1. There is only Single Valued Attributes.
2. Attribute Domain doesn’t change.
3. There is a Unique name for every Attribute or Column.
4. The order in which data is stored, doesn’t matter.

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