Data Normalization :: Essays Papers

info approach patternizationData publicization is an important step in any database pullulatement process. by means of this tedious process a developer can wipe out duplication and develop standards by which all data can be measured. This paper addresses the record and function of data commonization as it applies to the course at hand.In 1970, Dr. E.F. Codds seminal paper A Relational Model for Large shared Databanks was published in Communications of the ACM. This paper introduced the topic of data normalization, so-named because, at the time, President Nixon was normalizing analogys with China.Data normalization is a technique utilise during logical data modeling to ensure that there is only unmatchable way to know a fact, by removing all structures that provide more than superstar way to know the same fact as represent in a database relation (table). The goal of normalization is to control and eliminate redundancy, and mitigate the effects of modification anomalie s -- which are generally insertion and snub anomalies. (Insertion anomalies occur when the storage of information about one attri alonee requires additive information about a game judge. Deletion anomalies occur when the cutting off of one fact results in the loss of a second fact).NormalizationThere are six generally recognized normal forms of a relation first normal form, second normal form, third normal form, Boyce/Codd normal form, fourth normal form, and fifth normal form, also called jutting/join normal form. Other normal forms (e.g., Domain/Key) exist but will not be discussed here. The normal forms are hierarchical, i.e., each normal form builds upon its predecessor. Although many people consider a relation to be normalized only when it is in third normal form, technically speaking, a relation in only first normal form can be considered normalized. The Normal FormsFirst normal form (1NF) - All attributes must be atomic. That is, there can exist no repeating groups in a n attribute. For example, in a relation that describes a student, the students classes should not be stored in one field, separated by commas. Rather, the classes should be moved to their own relation, which should include a link back to the student relation (called a foreign key). siemens normal form (2NF) - A relation is in second normal form if it is in first normal form and each attribute is fully functionally qualified on the entire primary key. That is, no subset of the key can determine an attributes value.Third normal form (3NF) - A relation is in third normal form if it is in second normal form and each non-key attribute is fully functionally dependent on the entire primary key, and not on any other(a) non-key attribute.