Normalization in RDBMS.pptx
- 1. NORMALIZATION IN RDBMS S.B.S.Younus M.Sc., M.Phil., NET., Assistant Professor, Department of Information Technology, Sadakathullah Appa College, Tirunelveli. Follow on YouTube: SBS Digital Learning
- 2. WHAT IS NORMALIZATION? In a relational database management system (RDBMS), there are several normal forms (NFs) that help structure data to minimize redundancy and improve data integrity.
- 3. NORMALIZATION TYPES First Normal Form (1NF) Second Normal Form (2NF) Third Normal Form (3NF) Boyce Code Normal Form (BCNF) Fourth Normal Form (4NF) Fifth Normal Form (5NF)
- 4. FIRST NORMAL FORM (1NF) Ensures that each column in a table contains only atomic (indivisible) values. Example: Consider a table named "Students" with a column "Phone Numbers" that contains multiple phone numbers in a single cell. To achieve 1NF, we have to split the phone numbers into separate rows, each associated with a student.
- 5. SECOND NORMAL FORM (2NF) Extends 1NF and adds the requirement that each non-key column is functionally dependent on the entire primary key. Example: In a "Course Registration" table with student and course data, if the primary key is a combination of student ID and course ID, you should ensure that any data related to a course depends on both student ID and course ID.
- 6. THIRD NORMAL FORM (3NF) Extends 2NF and ensures that there is no transitive dependency between non- key columns. Example: In a "Library Books" table with columns for "Author" and "Author's Address," if the author's address depends on the author's name, you should create a separate "Authors" table to eliminate this transitive dependency.
- 7. BOYCE CODE NORMAL FORM (BCNF) BCNF is a stricter version of 3NF that deals with certain types of anomalies related to functional dependencies. It states that, for any non-trivial functional dependency X → Y in a relation, X must be a superkey (a set of attributes that uniquely identifies a tuple).
- 8. BCNF EXAMPLE Consider a "Students" table with attributes (columns) like StudentID, Course, and Professor. If you have a functional dependency where Course → Professor (i.e., each course is taught by a unique professor), and Course is not a superkey by itself, you need to decompose the table to meet BCNF. You'd create a new table for Courses and Professors, ensuring that Course (or a combination of attributes) serves as the key in the Courses table.
- 9. FOURTH NORMAL FORM (4NF) 4NF addresses multi-valued dependencies, where an attribute can have multiple values for a single set of other attributes. It requires that a relation be in BCNF and that there are no non-trivial multi-valued dependencies.
- 10. 4NF EXAMPLE Imagine a "Orders" table with attributes OrderID, CustomerName, and Item. If a single order can have multiple items, you'd split the table into "Orders" (containing OrderID and CustomerName) and "OrderItems" (containing OrderID and Item), ensuring that no multi-valued dependencies exist.
- 11. FIFTH NORMAL FORM (5NF) 5NF addresses cases where a relation contains join dependencies, ensuring that data can be reconstructed from decomposed tables without loss of information. It is used to handle complex cases where a relation needs to be split into multiple tables and joined when queried.
- 12. 5NF EXAMPLE Suppose you have a "Library" database with a "Books" table and a "Authors" table. 5NF would ensure that even after decomposing, you can still accurately retrieve information like which author wrote which book, by performing joins between the "Books" and "Authors" tables.
- 13. CONCLUSION Normal forms help organize data in a way that reduces redundancy and anomalies in a relational database, promoting data accuracy and consistency. Higher normal forms like BCNF, 4NF and 5NF address more complex dependencies and can be applied in specific scenarios as needed.