Extra Information on Normalization Justification (3NF)

 

🧾 Normalization Justification (3NF)

Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity. In this lab, we ensured the schema followed Third Normal Form (3NF). Below is the explanation for each normalization step:

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✅ First Normal Form (1NF) – Atomicity

• Rule: Each column must contain only atomic (indivisible) values. No repeating groups or arrays.

• How it was achieved:

  • All columns contain single values: e.g., StudentName, Email, CourseID.

  • There are no multi-valued fields like "Courses = ['Math', 'Physics']".

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✅ Second Normal Form (2NF) – Full Functional Dependency

• Rule: The table must be in 1NF, and all non-key attributes must be fully functionally dependent on the entire primary key (not just part of it).

• How it was achieved:

  • The Students table uses a single-column primary key (StudentID).

  • All other attributes in the Students table (e.g., StudentName, Age, Email, CourseID) depend only on StudentID.

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✅ Third Normal Form (3NF) – No Transitive Dependency

• Rule: The table must be in 2NF and no non-key attribute should depend on another non-key attribute (i.e., no transitive dependencies).

• Problem in unnormalized form:

  • Originally, Course was stored as a text field in the Students table.

  • This causes transitive dependency: StudentID → Course, but Course itself contains meaningful data (e.g., course name), which may relate to other course details.

• How it was fixed:

  • CourseName was moved into a new table called Courses.

  • Students now stores only CourseID as a foreign key, which refers to the Courses table.

  • This removes the dependency of CourseName on StudentID.

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🎯 Why 3NF is Important Here

• Prevents update anomalies (e.g., changing a course name in many rows).

• Prevents insertion anomalies (e.g., inserting a course before having a student).

• Prevents deletion anomalies (e.g., deleting a student and accidentally removing course info).

• Improves data consistency and integrity.

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💡 Summary Table

Normal Form	Rule	Achieved By
1NF	Atomic columns, no repeating groups	One value per cell in Students table
2NF	Full dependency on the primary key	All non-key attributes depend on StudentID
3NF	No transitive dependency	Moved CourseName to a separate Courses table

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