First Normal Form (1NF)
- A relation will be 1NF if it contains an atomic value.
- It states that an attribute of a table cannot hold multiple values. It must hold only single-valued attribute.
- First normal form disallows the multi-valued attribute, composite attribute, and their combinations.
Example: Relation EMPLOYEE is not in 1NF because of multi-valued attribute EMP_PHONE. EMPLOYEE table:
| EMP_ID |
EMP_NAME |
EMP_PHONE |
EMP_STATE |
| 14 |
John |
7272826385,
9064738238 |
UP |
| 20 |
Harry |
8574783832 |
Bihar |
| 12 |
Sam |
7390372389,
8589830302 |
Punjab |
The decomposition of the EMPLOYEE table into 1NF has been shown below:
| EMP_ID |
EMP_NAME |
EMP_PHONE |
EMP_STATE |
| 14 |
John |
7272826385 |
UP |
| 14 |
John |
9064738238 |
UP |
| 20 |
Harry |
8574783832 |
Bihar |
| 12 |
Sam |
7390372389 |
Punjab |
| 12 |
Sam |
8589830302 |
Punjab |
|