First Normal Form (1NF) :
A relation is said to be in first normal form (1NF) if it contains all atomic values.
The below relation is in 1NF.
Partial Dependency (PD) :
Let α → β be an FD.
Let γ is a proper subset of α. i.e., γ Ì α. And γ → β is also an FD.
Then, α → β is said to be ‘Partial Dependency’.
Here, β is said to be ‘partially dependent’ on α.
Second Normal Form (2NF) :
A relation is said to be in second normal form (2NF) if it does not contain ‘partial dependency’.
Example-1: In the relation given above, it is known that
A → C and AB → C
So, AB → C is called ‘Partial Dependency’.