First Normal Form (1NF)
- Eliminate duplicative columns from the same table.
- Create separate tables for each group of related data and identify each row with a unique column or set of columns (the primary key).
Second Normal Form (2NF)
- Meet all the requirements of the first normal form.
- Remove subsets of data that apply to multiple rows of a table and place them in separate tables. Create relationships between these new tables and their predecessors through the use of foreign keys.
Third Normal Form (3NF)
- Meet all the requirements of the second normal form.
- Remove columns that are not dependent upon the primary key.
Fourth Normal Form (4NF)
- Meet all the requirements of the third normal form.
- A relation is in 4NF if it has no multi-valued dependencies.