
Overview of Relational DBMS
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normal form or not. Initially, three normal forms were introduced, namely, 1NF (First normal form),
2NF (Second normal form) and 3NF (Third normal form). In 1974, a stronger version of 3NF called
Boyce–Codd normal form (BCNF) was developed. All these normal forms are based on functional
dependencies among the attributes in a relation. Later, higher normal forms such as 4NF (Fourth
normal form) and 5NF (Fifth normal form) were introduced. 4NF is based on multi-valued depen-
dencies, while 5NF is based on join dependencies.
The process of normalization is a formal method in which a single relation is decomposed into ...