Explain Project Join Normal Form PJNF with example.
Database Management System
Computer Science Engineering
720
Deepak
Fifth normal form (5NF), also known as projection–join normal form (PJ/NF), is a level of database normalization designed to remove redundancy in relational databases recording multi-valued facts by isolating semantically related multiple relationships.
Fifth normal form (5NF), is also known as project-join normal form (PJNF). It is a level of database normalization designed to reduce redundancy in relational databases. A relation is said to be in 5NF if and only if it satisfies 4NF and no join dependency exists.
Condition for join dependency:
If the join of R1 and R2 over Q is equal to relation R then we can say that a join dependency exists, where R1 and R2 are the decomposition R1 (P, Q) and R2 (Q, S) of a given relation R (P, Q, S). R1 and R2 are a lossless decomposition of R.
Database normalization is the method of restructuring a relational database in accordance with a set of so-called normal forms to minimize data complexity and increase data integrity. Fifth normal form (5NF), also known as project-join normal form (PJNF) is a level of database normalization designed to minimize duplication in relational databases. A relation is supposed to be in 5NF if and just on the off chance that it fulfills 4NF and no join reliance exist.