What is Normalization ? What are the types of Normalization ? What is BCNF ?

The formal classifications describing the level of database normalization in a data model are called Normal Forms (NF) and the process of doing this is Normalization.

First normal form

First normal form (1NF) lays the groundwork for an organised database design:

• Ensure that each table has a primary key: minimal set of attributes which can uniquely identify a record.


• Eliminate repeating groups (categories of data which would seem to be required a different number of times on different records) by defining keyed and non-keyed attributes appropriately.


• Atomicity: Each attribute must contain a single value, not a set of values.


• 'First normal form' depends on functional dependency formula f(x)=y. For every value of x there is value for y.

Second normal form

Second normal form (2NF) If a table has a composite key, all attributes must be related to the whole key:

• The database must meet all the requirements of the first normal form.


• The relational schema should not have any partial functional dependency i.e. No proper subset of the primary key should derive a functional dependency belonging to the same schema. For example, consider functional dependencies FD:{AB->C, A->D, C->D} here AB is the primary key, as A->D this relational schema is not in 2NF.

Third normal form

Third normal form (3NF) requires that data stored in a table be dependent only on the primary key, and not on any other field in the table.

• The database must meet all the requirements of the first and second normal form.


• All fields must be directly dependent on the primary key field. Any field which is dependent on a non-key field which is in turn dependent on the Primary Key (ie a transitive dependency) is moved out to a separate database table.

Boyce-Codd normal form

Boyce-Codd normal form (or BCNF) requires that there be no non-trivial functional dependencies of attributes on something other than a superset of a candidate key (called a superkey).

I don't think so that You will be need to know any other advance Normalization forms.