Single valued normalisation, Database Management System

Single Valued Normalisation

 Codd in the year 1972 formed three normal forms (1NF, 2NF, and 3NF). These were based on functional dependencies between the attributes of a relation. Later Codd and Boyce proposed another normal form known as the Boyce-Codd normal form (BCNF). The fourth and fifth normal forms are based on multivalue and join dependencies and were proposed soon.  In this part we will do normal forms till BCNF only. Fourth and fifth normal forms are afar the scope of this course. For all practical purposes, BCNF or the3NF are quite adequate since they remove the anomalies talk about for most common situations. It should be obviously understood that there is no obligation to normalise relations to the maximum possible level. Performance should be engaged into account and sometimes an organisation may take a decision not to normalise, say, beyond third normal form. But, it should be noted that such designs should be careful sufficient to take care of anomalies that would result as of the decision above.

Intuitively, the second and third normal forms are planned to result in relations such that each relation have information about only one thing (either an relationship or a entity). A sound E-R model of the database would make sure that all relations either give facts about an entity or about a relationship resulting in the relations that are get being in 2NF or 3NF.

Normalisation results in decomposition of the original relation. It should be noted that decomposition of relation has to be always rely on principles, such as functional dependence, that ensure that the original relation may be reconstructed from the decomposed relations if and when needed. Careless decomposition of a relation can result in loss of information. We will talk about this in detail in the later section. Let us now describe these normal forms in more detail.

 

Posted Date: 3/7/2013 1:54:39 AM | Location : United States







Related Discussions:- Single valued normalisation, Assignment Help, Ask Question on Single valued normalisation, Get Answer, Expert's Help, Single valued normalisation Discussions

Write discussion on Single valued normalisation
Your posts are moderated
Related Questions
Explain controlled redundancy? Controlled redundancy : The replication of data within the data warehouse for the purposes of improved data access or understand ability.

What is a Phantom Deadlock? In distributed deadlock detection, the delay in propagating local information might cause the deadlock detection algorithms to recognize deadlocks

A TDMS project plan is not a typical Information Technology project plan; therefore, a traffic data project has several unique characteristics: Traffic data management system

Define access time. Access time is the time from when a read or write request is issued to when data transfer starts.

What is a view? A view is a logical view on one or more tables.  A view on one or more tables i.e., the data from a view is not actually physically kept instead being derived f

Australian Bureau of Statistics (ABS) provides retail data for different groups and different states as well as the aggregate numbers. Table 11 " Retail Turnover, State by Industry

Let us first look into some of the important features of ER model. Entity relationship model is a high-level conceptual data model. It permits us to define the data invo

What is Structured Query Langauge (SQL)? SQL is a powerful set-oriented language which was formed by IBM research for the databases that adhere to the relational model. It havi

What is called as recursive partitioning? The system repeats the splitting of the input unless each partition of the build input fits in the memory. Such partitioning is known

Question: AirwaysCentre, an international airline booking company currently uses a relational database system for their operations, which includes the following relations: P