Normalization is a name given to the process of simplifying the relationship among data element on a record. Normalization replace a collection of data in a record structure by other record design which is simpler more predictable and there for more manageable. Goal of a relational database design is to generate set of relation schemes that allow is to store information without any redundant data. Normalization also allow to retrieve information easily.
UNF :- If the table contains non-atomic value at each row. It is called un-normalized form.
First Normal Form :- A table in the First Normal From, when it is contain non-repeating groups. A repeating columns or fields present in an un-normalized table are removed from to table and put into separate table or tables. These table are dependent on the present table form which it is derived. The key to those table must also be part of the present table the present and derived table can be related to each other.
Second Normal Form :- A table in the Second Normal Form, if all it non-key fields are fully dependent on the whole key. Those that do not depend upon a combination key are removed to another table on whose key the depend on.
Third Normal ‘Form :- A table in the Third Normal Form. If all non-key fields of a table are independent of all other non-key fields of a table.
Boyce_codd Normal Form :- BCNF was proposed as a simple form of 3NF, but it is more strict the 3NF, meaning that every relation in BCNF is also in 3NF. Relation in 3NF is not necessary in BCNF.