A relation is said to be in 1-NF if and only if all the values in the relation are atomic and there are no multi valued attributes.
Note: According to CODD’s rule of RDBMS each and every relation shall exist in 1-NF minimum in Relational Database.
A relation is said to be in 2-NF if and only if:
- It exists in 1-NF
- It does not have any partial dependencies.
Note: 2-NF eliminates all the partial dependencies hence all the dependencies caused by partial dependencies also gets eliminated.
A relation is said to be in 3-NF if and only if:
- It exists in 2-NF
- It does not have any Transitive dependencies.
Note: 3-NF eliminates both partial and transitive dependencies and hence the redundancies caused by them would get eliminated.
BCNF (Boyce Codd Normal Form):
A relation is said to be in BCNF if and only if:
- It exists in 3-NF.
- It does not have any Overlapping candidate key dependencies.
Hierarchy of Normal Forms: