Normalization in DBMS

  • The normalization process, as first proposed by Codd (1972a), takes a relation schema through a series of tests to certify whether it satisfies a certain normal form.
  • The process, which proceeds in a top-down fashion by evaluating each relation against the criteria for normal forms and decomposing relations as necessary, can thus be considered as relational design by analysis.
  • If we had a method of breaking up such a large table into smaller tables so that these types of problems would be eliminated, the database would be much more efficient and reliable
  • Classes of relational database schemes or table definitions, called normal forms, are commonly used to accomplish this goal. The creation of a normal form database table is called normalization.
  • Normalization is accomplished by analyzing the interdependencies among individual attributes associated with those tables and taking projections (subsets of columns) of larger tables to form smaller ones.
  • Normalization is a formal process for determining which fields belong in which tables in a relational database. Normalization follows a set of rules worked out at the time relational databases were born.
  • Normalization of data can be considered a process of analyzing the given relation schemas based on their FDs and primary keys to achieve the desirable properties of (1) minimizing redundancy and (2) minimizing the insertion, deletion, and update

  • Unsatisfactory relation schemas that do not meet certain conditions—the normal form tests—are decomposed into smaller relation schemas that meet the tests and hence possess the desirable properties
  • Thus, the normalization procedure provides database designers with the following:
    • A formal framework for analyzing relation schemas based on their keys and on the functional dependencies among their attributes.
    • A series of normal form tests that can be carried out on individual relation schemas so that the relational database can be normalized to any desired degree.
  • The normal form of a relation refers to the highest normal form condition that it meets, and hence indicates the degree to which it has been normalized.
  • A normalized relational database provides several benefits:
    • Elimination of redundant data storage.
    • Close modeling of real world entities, processes, and their relationships.
    • Structuring of data so that the model is flexible.
    • Normalization ensures that you get the benefits relational databases offer. Time spent learning about normalization will begin paying for itself immediately.

Types of Normalization