15 November 2018
Normalization is the process of successively reducing relations with anomalies to produce smaller, well-structured relations.
It makes no assumptions about how data will be used in displays, queries, or reports. It places no constraints on how data can or should be physically stored or,therefore, on processing performance. Normalization is a logical data modeling technique used to ensure that data are well structured from an organization-wide view. It is a process of organizing the data in database to avoid data redundancy, insertion anomaly, update anomaly & deletion anomaly.
Normalizations consists of set of procedures that eliminates the domains that are non-atomic and redundancy of data that prevents data manipulation and loss of data integrity.
Most commonly used normal forms:
There are 9 normalizations that are used inside the database. These are shown in below table:
|First normal form||This table represents a relation/entities with no repeating groups of attributes|
|Second normal form||Non- prime attributes are not functional dependent on subset of any candidate key|
|Third normal form||In a table every non- prime attribute is non-transitively dependent on every candidate key|
|Elementary key normal form||superkey dependency or elementary key dependency effects the functional dependency in a table|
|Boyce codd normal form||every non-trivial functional dependency in the table is dependent on superkey|
|Fourth normal form||Every non-trivial multivalued dependency in the table is a dependent on a superkey|
|Fifth normal form (5NF)||Every non-trivial join dependency in the table is implied by the superkeys of the table|
|Domain/key normal form (DKNF)||Every constraint on the table is a logical consequence of the table’s domain constraints and key constraints|
|Sixth normal form (6NF)||Table features no non-trivial join dependencies at all|
Non-first normal form (NFA)
– It describes the definition of the database design which is different from the first normal form.
It is a type of database which is optimized for data warehouse and online analytical processing(OLAP) applications. This database are normally created from the inputs obtained from existing relational databases.
Relational database can be accessed using a SQL query whereas a multidimensional database allows a user to answer analytical question from those relational database.Multidimensional database is mainly used to summarize business operations and trends.
Jeffrey A. Hoffer, Ramesh Venkataraman, and Heikki Topi. 2010. Modern Database Management (10th ed.). Prentice Hall Press, Upper Saddle River, NJ, USA.