Editing Second normal form (section)

{{Short description|Term in database normalization}}{{More footnotes needed|date=June 2024}}

'''Second normal form''' ('''2NF'''), in [[database normalization]], is a [[Database normalization#Normal forms|normal form]]. A relation is in the second normal form if it fulfills the following two requirements:
# It is in [[first normal form]].
# It does not have any [[non-prime attribute]] that is [[Functional dependency|functionally dependent]] on any [[proper subset]] of any [[candidate key]] of the relation (i.e. it lacks partial dependencies). A ''non-prime attribute of a relation'' is an attribute that is not a part of any candidate key of the relation.

Put simply, a relation (or table) is in 2NF if: 
# It is in 1NF and has a single attribute [[unique identifier]] (UID) (in which case every non key attribute is dependent on the entire UID), or 
# It is in 1NF and has a multi-attribute unique identifier, and every regular attribute (not part of the UID) is dependent on ''all attributes'' in the multi-attribute UID, not just one attribute (or part) of the UID. 
If any regular (non-prime) attributes are predictable (dependent) on another (non-prime) attribute, that is addressed in [[third normal form]].