Chapter :-4 (English)

5. Main Normal Forms (NF) in Normalization

Main Normal Forms (NF) in Normalization

1. First Normal Form (1NF)

Definition:

• No repeating groups
• All values are atomic (single-valued)

ü Advantages:

• Eliminates duplicate columns
• Makes data easier to search and sort
• Ensures a consistent structure

ü Disadvantages:

• May still contain redundancy
• Anomalies (update, insert, delete) can still occur

 

  2.  Second Normal Form (2NF)

Definition:

• Must be in 1NF
• No partial dependency (non-key attributes must depend on the whole primary key)

ü Advantages:

• Reduces redundancy in tables with composite keys
• Removes partial dependency problems
• Reduces insert/update anomalies further

ü Disadvantages:

• Increases number of tables
• More joins needed

 

 3. Third Normal Form (3NF)

Definition:

• Must be in 2NF
• No transitive dependency (non-key attribute depending on another non-key attribute)

ü Advantages:

• Removes most redundancy
• Minimizes anomalies significantly
• Produces well-structured and efficient tables

ü Disadvantages:

• More tables → more complexity
• May slow down queries that need to combine data

 

4. Boyce–Codd Normal Form (BCNF)

Definition:

• Stronger version of 3NF
• For every Functional Dependency X → Y, X must be a superkey

ü Advantages:

• Eliminates all anomalies not fixed by 3NF
• Ensures a very high level of data consistency
• Ideal for mission-critical systems

ü Disadvantages:

• Can cause excessive splitting of tables
• Might require many joins, reducing performance
• Harder to design and understand

 Table form

Normal Form	Main Goal	Advantage	Disadvantage
1NF	Atomic values, no repeating groups	Simple structure	Still redundant
2NF	Remove partial dependencies	Less redundancy	More tables
3NF	Remove transitive dependencies	Eliminates most anomalies	More joins needed
BCNF	Every determinant is a superkey	Highest consistency	Very complex, may hurt performance