Student Details: Fundamentals Of Databases It 403 2 Marks

Student Detailsname Fundamentals Of Databases It 403 2 Marksque

Normalize the following schema, with given constraints, to BCNF. books(accessionno, isbn, title, author, publisher) users(userid, name, deptid, deptname) accessionno isbn isbn title isbn publisher isbn author userid name userid deptid deptid deptname

Answer 1NF : Select primary key for each relation books(accessionno, isbn, title, author, publisher) users(userid, name, deptid, deptname)

2NF: All relations are in 2NF because the primary key is a single attribute: books(accessionno, isbn, title, author, publisher) users(userid, name, deptid, deptname)

3NF: Prevent any transitively dependent in the 2NF relations. Also, all relations are in BCNF: books(isbn, title, publisher, author), accession(accessionno, isbn), user(userid, name, deptid), department(deptid, deptname)

Paper For Above instruction

Normalization is a fundamental process in database design that aims to organize data efficiently by eliminating redundancy and dependency anomalies. The process of normalization involves decomposing complex relations into simpler, well-structured relations that adhere to specific normal forms, with BCNF (Boyce-Codd Normal Form) being the most stringent among them. This essay discusses the normalization of given schemas to BCNF, focusing on the principles of each normal form, the step-by-step approach taken to achieve BCNF, and the importance of normalization in robust database design.

The initial schemas under consideration are the 'books' and 'users' relations. The 'books' relation contains attributes: accessionno, isbn, title, author, publisher. The 'users' relation comprises userid, name, deptid, deptname. The first step in normalization is to identify the primary keys for each relation. For 'books,' the primary key is likely accessionno, as it uniquely identifies each book copy, whereas for 'users,' userid uniquely identifies each user. These primary keys are essential for establishing functional dependencies and progressing through the normal forms.

In First Normal Form (1NF), the primary requirement is that all attributes must contain atomic (indivisible) values, and there should be no repeating groups. Both schemas already meet 1NF, as each attribute contains atomic values. The next step is to verify 2NF, which requires that every non-prime attribute is fully functionally dependent on the primary key. Since in these schemas the primary keys are single attributes (accessionno and userid), and there are no partial dependencies, the schemas are considered to be in 2NF.

Advancing to Third Normal Form (3NF) involves eliminating transitive dependencies—situations where a non-prime attribute depends on another non-prime attribute, which in turn depends on the primary key. In the 'books' schema, attributes such as title, author, and publisher are dependent on isbn, which is a unique identifier for the book's bibliographic information. Similarly, in 'users,' deptname depends on deptid. These dependencies suggest that while the relations are in 3NF, further decomposition is necessary to reach BCNF, which requires that every determinant be a candidate key.

To achieve BCNF, the relations must be decomposed such that determinants are candidate keys. For the 'books' relation, since isbn determines title, author, and publisher, and isbn is not part of the primary key (which is accessionno), a decomposition is necessary. We create separate relations: one for the ISBN details—isbn, title, author, publisher—and another for accession numbers linked via isbn, ensuring that the determinants (isbn) are candidate keys within their relations. Similarly, for 'users,' since deptid determines deptname, a separate 'department' relation is created with deptid and deptname. The 'users' relation then references deptid as a foreign key, thus meeting BCNF criteria.

The normalized schema thus consists of the following relations:

  • books: accessionno, isbn (primary key)
  • isbn_details: isbn, title, publisher, author (primary key: isbn)
  • user: userid, name, deptid
  • department: deptid, deptname

This decomposition ensures that every determinant is a candidate key in its relation, thereby satisfying BCNF. This approach minimizes redundancy and prevents update anomalies, facilitating consistent and efficient data management.

In conclusion, normalization to BCNF involves analyzing functional dependencies and decomposing relations to ensure that determinants are candidate keys. This process not only enhances data integrity but also optimizes database performance. Correct normalization, such as demonstrated here, is vital for developing robust, maintainable, and scalable database systems.

References

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