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The Boyce–Codd normal form was first described by Ian Heath in 1971, and has also been called Heath normal form by Chris Date. [ 1 ] BCNF was formally developed in 1974 by Raymond F. Boyce and Edgar F. Codd to address certain types of anomalies not dealt with by 3NF as originally defined.
Codd went on to define the second normal form (2NF) and third normal form (3NF) in 1971, [5] and Codd and Raymond F. Boyce defined the Boyce–Codd normal form (BCNF) in 1974. [6] Ronald Fagin introduced the fourth normal form (4NF) in 1977 and the fifth normal form (5NF) in 1979. Christopher J. Date introduced the sixth normal form (6NF) in 2003.
Fourth normal form (4NF) is a normal form used in database normalization. Introduced by Ronald Fagin in 1977, 4NF is the next level of normalization after Boyce–Codd normal form (BCNF). Whereas the second , third , and Boyce–Codd normal forms are concerned with functional dependencies , 4NF is concerned with a more general type of ...
The third normal form (3NF) is a normal form used in database normalization. 3NF was originally defined by E. F. Codd in 1971. [2] Codd's definition states that a table is in 3NF if and only if both of the following conditions hold: The relation R (table) is in second normal form (2NF).
Boyce–Codd normal form (BCNF) was developed in 1974 by Boyce and Edgar F. Codd. It is a type of normal form that is used in database normalization. The goal of relational database design is to generate a set of database schemas that store information without unnecessary redundancy. Boyce-Codd accomplishes this and allows users to retrieve ...
The third normal form, Boyce–Codd normal form, fourth normal form and fifth normal form are special cases of the domain/key normal form. All have either functional, multi-valued or join dependencies that can be converted into superkeys. The domains on those normal forms were unconstrained so all domain constraints are satisfied.
For example, an JSON or XML database might support duplicate records and intrinsic ordering. Such database can be described as non-relational. But there are also database models which support the relational view, but does not embrace first normal form. [4] Such models are called non-first normal form relations (abbreviated NFR, N1NF or NF 2).
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