I)First Normal Form (1NF)
A relation R is in First Normal Form (1NF) if all underlying
domains contain atomic values only.
All occurrences of a record type must contain the same
number of fields.
No repeating groups.
II)Second Normal Form (2NF)
A relation R is in second normal form (2NF) if it is in 1NF
and every attribute is fully dependent on the primary key.
Alternate definition.
In 1NF and one of the following conditions holds:
a) Key consists of a single attribute
b) There are no nonkey attributes
c) Every nonkey attribute depends on all of the key.
III)Third Normal Form (3NF)
A relation R is in third normal form (3NF) if it is in
2NF and every nonkey attribute is nontransitively dependent
on the pprimary key.
Alternate definition:
A relation R is in 3NF IFF the nonkey attributes of R (if any)
are:
a) Mutually independent, and
b) Fully dependent on the primary key of R.
IV)Boyce-Codd Normal Form (BCNF)
The 3NF does not deal satisfactorily with the case of a relation
that:
a) Has multiple candidate keys, where
b) Those candidate keys are composite, and
c) The candidate keys overlapped
(i.e., have at least one attribute in common).
V)Fourth Normal Form (4NF)
In BCNF and a relation should not contain two or more
independent multivalued dependencies on a given entity.
VI)Fifth Normal Form (5NF)
A relation R is in fifth normal form (5NF)-also called
projection-join normal form (PJ/NF) if every join dependency
in R is a consequence of the candidate keys of R.
A relation R(A,B,..,Z) satisfies the join dependency (JD)
if R is equal to the join of its projections on A,B,..,Z where
A,B,..,Z are subsets of the set of attributes of R.