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Fourth Normal Form (4NF) in DBMS
Understanding 4NF:
Fourth Normal Form (4NF) is a level of database normalization where a table is in BCNF and all multi-valued dependencies are removed. This ensures that there are no non-trivial multi-valued dependencies other than a candidate key.
Importance of 4NF:
4NF helps in eliminating redundancy and ensures data integrity by removing unnecessary duplications, especially when dealing with complex relationships involving multi-valued dependencies.
4NF Example:
Consider a table storing information about students, their courses, and hobbies. If a student can have multiple courses and hobbies, this creates multi-valued dependencies.
// Original Table with Multi-Valued Dependencies
| StudentID | Course | Hobby |
|-----------|----------|-----------|
| 1 | Math | Painting |
| 1 | Science | Painting |
| 1 | Math | Music |
| 1 | Science | Music |
// Decomposed Tables in 4NF
// Student-Course Table
| StudentID | Course |
|-----------|----------|
| 1 | Math |
| 1 | Science |
// Student-Hobby Table
| StudentID | Hobby |
|-----------|----------|
| 1 | Painting |
| 1 | Music |
Benefits of 4NF:
By decomposing the original table into two separate tables, we eliminate redundancy and ensure that each table contains data that is uniquely dependent on the primary key.
Challenges in 4NF:
While achieving 4NF can reduce redundancy, it might also result in increased complexity in querying data as more joins might be required.
Console Output:
Data in 4NF is organized efficiently to eliminate redundancy.
