5th Normal Form(5NF) in DBMS
• Database Management Systems | Data
Normalization
2.
Introduction to Normalization
•- What is Normalization?
• Process of organizing data to reduce
redundancy and improve data integrity.
• - Why Normalize?
• - Minimize duplication
• - Ensure data consistency
• - Facilitate efficient data management
3.
Quick Recap ofPrevious Normal
Forms
• - 1NF: Eliminate repeating groups
• - 2NF: Remove partial dependencies
• - 3NF: Remove transitive dependencies
• - BCNF: A stricter version of 3NF
• - 4NF: Remove multi-valued dependencies
4.
What is 5thNormal Form (5NF)?
• - Also known as Project-Join Normal Form
(PJNF)
• - A table is in 5NF if:
• - It is in 4NF
• - It cannot be further non-loss decomposed
into smaller tables
5.
Key Concept Behind5NF
• - Deals with join dependency and lossless
decomposition.
• - Decomposition should not result in loss of
information when tables are joined back.
6.
Join Dependency
• -A table T satisfies a join dependency if T can
be recreated by joining multiple projections of
T without loss of information.
• - Example:
• JD(R1, R2, R3) means T = R1 R2 R3
⨝ ⨝
7.
When is 5NFNeeded?
• - Complex relationships involving multi-
attribute dependencies.
• - Rare in practice but critical in certain
business databases (e.g., contract
management, supplier-part-project).
8.
Example Scenario
• -Supplier-Product-Project Example:
• - A supplier supplies a product for a project.
• - Decomposition:
• - Supplier-Product
• - Supplier-Project
• - Product-Project
• - Rejoining must perfectly recreate the original
table.
9.
Importance of 5NF
•- Eliminates redundancy caused by join
dependencies.
• - Ensures data integrity for complex scenarios.
• - Helps in very fine-grained database design.
