Data Normalization - Information Systems Reengineering, Integration and Normalization - page 339

Student ID Student Age

FD : Student ID ====== Student Age
determines

Fig. 9.3 Data determination of functional dependency

superclass data. Multivalued dependency implies that each determinant can deter-
mine a multiple value. Join dependency implies that the join of all of its attributes
implies the n-ary relationship within the relation.
In general, a functional dependency describes the relationship between attributes
such that a determinant (key field) determines dependent (non-key) fields as shown
below (Fig. 9.3 ):

Determines
FD: Determinant Dependent field

A relation is in first normal form (1NF) if all attributes are atomic value, and there
is a primary key attribute with uniquely identifiable value which can determine
non-key attributes.

Normalized into

UNF 1NF

Eliminate multiple valued attributes

For example, after normalization by transforming multiple valued attributes into
atomic single value, the UNF becomes first normal form as follows:

Relation R ( S# , S-Name, Enroll) is a 1NF where all attributes are atomic
with S# as primary key..

A relation is in second normal form (2NF) if there is no partial data dependency
(PFD) with the relation.

Normalized into

1NF 2NF

Eliminate partial functional dependency