2. AIM OFTHE SESSION
To familiarize students with the basic concept i.e., to break down complex ideas or concepts into
simpler, more manageable parts or components.
INSTRUCTIONAL OBJECTIVES
This Session is designed to facilitate understanding and analysis of complex ideas or concepts by
breaking them down into simpler components.
LEARNING OUTCOMES
At the end of this session we should be able improved understanding, problem-solving, communication, critical
thinking, decision-making, creativity, organizational skills, and domain knowledge.
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6. FOURTH NORMAL FORM-4NF
A multivalued dependency X → Y specified on relation schema R, where X and Y are both subsets
of R, specifies the following constraint on any relation state r of R:
If two tuples t1 and t2 exist in r such that t1[X] = t2[X], then two tuples t3 and t4 should also exist
in r with the following properties, where we use Z to denote (R − (X ∪ Y)):
Definition:
A Relation R is in 4NF if and only if the following conditions are satisfied
(i) R is in already BCNF or 3NF
(ii) R contains no MVDs
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26. Keeping both the relations separately will results a Good database design
35. ACTIVITIES/ CASE STUDIES/ IMPORTANT FACTS RELATED TO THE
SESSION
Case Studies
1.Student Information Normalization
A university collects student data such as names, addresses, course enrollments, and grades in a database. However, they
notice that the same student can have multiple entries in the database, one for each course they’ve taken. This creates redundancy
and makes it difficult to manage the data. To normalize the data, they create separate tables for students, courses, and enrollments,
and then use IDs to link them together.This ensures that each piece of data is stored only once and can be easily updated.
2.Employee Normalization
A company has a database with information on employees, including their names, addresses, job titles, and salaries. However,
they notice that some employees have multiple job titles, which creates redundancy in the data. To normalize the data, they create
separate tables for employees and job titles, and then use a linking table to connect them. This ensures that each employee has
only one record in the database, and makes it easier to manage changes to job titles and salaries.
36. EXAMPLES
First Normal Form (1NF)
This is the simplest form of normalization, which requires that all data in a table is atomic, i.e., it cannot be further divided
into smaller pieces. For example, in a table of customer information, the name column should be split into separate columns for
first name and last name to satisfy 1NF.
Second Normal Form (2NF)
This form requires that each non-key attribute in a table is dependent on the table's primary key. In other words, if a
column's value can be determined by combining values in other columns, it should be moved to a separate table. For example, in a
table of orders, the product name and price should be moved to a separate table, as they depend on the product ID.
37. EXAMPLES
Third Normal Form (3NF)
This form requires that all non-key attributes in a table are independent of each other. In other words, if a column depends
on another non-key column, it should be moved to a separate table. For example, in a table of customers and their orders, the
customer's address should be moved to a separate table, as it depends only on the customer ID, not on the order.
Boyce-Codd Normal Form (BCNF)
This form is similar to 3NF, but it goes further by requiring that every determinant (a column or set of columns that uniquely
determines another column) is a candidate key (a minimal set of columns that can uniquely identify each row in a table). This
ensures that there are no anomalies or redundancies in the data.
38. SUMMARY
Overall, normalization is a process of organizing data in a database to reduce redundancy, improve data consistency,
and make it easier to manage and update the data.
39. SELF-ASSESSMENT QUESTIONS
1. What is the purpose of normalization in a database?
a) To increase data redundancy
b) To reduce data redundancy
c) To make it difficult to manage data
d) To increase data inconsistency
2. Which form of normalization goes further than 3NF by requiring that every determinant is a
candidate key?
(a) First Normal Form (1NF)
b) Second Normal Form (2NF)
c) Third Normal Form (3NF)
d) Boyce-Codd Normal Form (BCNF)
40. TERMINAL QUESTIONS
1. What is a candidate key in a database table?
2.What is the relationship between normalization and data redundancy?
3. Create a normalized database schema from an unnormalized set of data.
4.Analyze a database schema to determine if it meets the requirements of a specific normal form.
5. Determine if a given normalization level is sufficient for a particular database.
6. Create a normalized database schema that includes multiple tables and relationships.
41. REFERENCES FOR FURTHER LEARNING OF THE SESSION
Reference Books:
1. "Database Management Systems" by Raghu Ramakrishnan and Johannes Gehrke - This is a comprehensive textbook
that covers both theoretical and practical aspects of DBMS, including data modeling, relational algebra, SQL, query
optimization, transaction management, and distributed databases.
2. "Fundamentals of Database Systems" by Ramez Elmasri and Shamkant Navathe - This is another popular textbook
that covers the fundamental concepts of DBMS, including database design, normalization, SQL programming,
transaction management, and concurrency control.
Sites andWeb links:
1. https://www.tutorialspoint.com/Lossless-and-Lossy-Decomposition-in-DBMS
2. https://www.javatpoint.com/decomposition-algorithms
