• First NF: Duplicate columns should be eliminated.
  • Second NF: Should be 1NF. Should remove subsets of data that repeats in multiple rows and place them in separate table.
  • Third NF: Should be in 2NF. Repeat columns that are not dependent upon the primary key.
  • Boyce-Codd NF: Should be in 3NF. A relation is in BCNF if every determinant is a candidate key.
  • Fourth NF: Should be in 3NF and BCNF. A relation is in 4NF if it has no more than one multi-valued or multiple dependencies.