Normalization Process Concepts | Database Management System

Normalization Process Concepts | Database Management System

 

Normalization is a process in which an initial DB design is transformed, or decomposed, into a different, but equivalent, design. The resulting schema is equivalent to the original one in the sense that no information is lost when going from one to the other.

The normalization procedure consists of a sequence of projections – that is, some attributes are extracted from one tabletoform a new one. In other words, tables are split up vertically. The decomposition is lossess, only if you can restore the original table by joining its projections. Through such non-loss decompositions it is possible to transforman original schema into a resulting one that satisfies certain conditions, known as Normal Forms:

  • The First Normal Form (1 NF) addresses the structure of an isolated table.
  • The Second (2NF), Third (3.NF), and Boyce-Codd (BCNF) Normal Forms address one-to-one and one-to-many relationships.
  • The Fourth (4NF) and Fifth (5NF) Normal Forms deal with many-to-many relationships. These Normal Formsform a hierarchy in such away that a schemain a higher normal form automatically fulfills all the criteria for all of the lower Normal Forms.

The Fifth Normal Form is the ultimate normal form with respect to projections and joins – it is guaranteed to be free of anomalies that can be eliminated by taking projections.