Summary of All Normal Forms

Introduction

• Summary of all Normal Forms: 1NF, 2NF, 3NF, BCNF, 4NF, 5NF
• Detailed videos available separately
• Real-life examples provided to understand scenarios in each Normal Form
• Useful for exams and interviews

First Normal Form (1NF)

• Condition: No Multi-Valued Attribute (Atomic/Single Value Attribute)
• Example:
  • Roll number with multiple courses (e.g., "1, C C++") is not in 1NF
• Solution: Split multi-valued attribute into different rows or tables

Second Normal Form (2NF)

• Condition:
  • Table must be in 1NF
  • No Partial Dependency
• Explanation:
  • AB (candidate key) determines C
  • No subset of candidate key should partially determine a non-unique attribute
• Example: Scenario of a company with co-founders A and B

Third Normal Form (3NF)

• Condition:
  • Table must be in 2NF
  • No Transitive Dependency
• Explanation:
  • X (candidate key) determines Y (non-unique)
  • Y determines Z (non-unique)
  • X indirectly determines Z (transitively)
• Problem: Y being non-prime causes issues
• Example: Classroom scenario with topper X, friend Y, and another friend Z

Boyce-Codd Normal Form (BCNF)

• Condition:
  • Table must be in 3NF
  • Left side of every dependency must be a candidate key or super key
• Goal: Eliminate redundancy completely

Fourth Normal Form (4NF)

• Condition:
  • Table must be in BCNF
  • No Multi-Valued Dependency
• Explanation: Example with person "Varun" having multiple phone numbers and emails
• Solution: Decompose into separate tables to avoid redundancy

Fifth Normal Form (5NF)

• Condition:
  • Table must be in 4NF
  • Lossless Decomposition
• Goal: Avoid lossy decomposition and spurious tuples
• Solution: Ensure common attribute is a candidate key

Conclusion

• Basic summary of all normal forms provided
• Detailed explanations available through provided links in the description