Normalization in DBMS
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Normalization is a process used to organize data in a database. It involves breaking tables into smaller, more manageable pieces to reduce data redundancy and improve data integrity. There are several normal forms including 1NF, 2NF, 3NF, BCNF, 4NF and 5NF. The document provides examples of tables and how they can be decomposed into different normal forms to eliminate anomalies and redundancy through the creation of additional tables and establishing primary keys.
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Normalization in DBMS
- 1. NORMALIZATION & TYPES OF NORMALIZATION
- 2. 1) DEFINE NORMALIZATION Normalization can be defined as :- A process of organizing the data in database to avoid data redundancy, insertion anomaly, update anomaly & deletion anomaly. • A process of organizing data into tables in such a way that the results of using the database are always unambiguous and as intended. Such normalization is intrinsic to relational database theory. It may have the effect of duplicating data within the database and often results in the creation of additional tables.
- 3. Types of normalization First Normal Form (1NF) Second Normal Form (2NF) Third Normal Form (3NF) Boyce-Codd Normal Form (BCNF) Fourth Normal Form (4NF) Fifth Normal Form (5NF)
- 4. First Normal Form (1NF) First normal form enforces these criteria: Eliminate repeating groups in individual tables. Create a separate table for each set of related data. Identify each set of related data with a primary key
- 5. First Normal Form Table_Product Product Id Colour Price 1 Black, red Rs.210 2 Green Rs.150 3 Red Rs. 110 4 Green, blue Rs.260 5 Black Rs.100 This table is not in first normal form because the “Colour” column contains multiple Values.
- 6. After decomposing it into first normal form it looks like: Product_id Price 1 Rs.210 2 Rs.150 3 Rs. 110 4 Rs.260 5 Rs.100 Product_id Colour 1 Black 1 Red 2 Green 3 Red 4 Green 4 Blue 5 Black
- 7. Second Normal Form (2NF) A table is said to be in 2NF if both the following conditions hold: Table is in 1NF (First normal form) No non-prime attribute is dependent on the proper subset of any candidate key of table. An attribute that is not part of any candidate key is known as non-prime attribute.
- 8. SECOND NORMAL FORM Table purchase detail Customer_id Store_id Location 1 1 Patna 1 3 Noida 2 1 Patna 3 2 Delhi 4 3 Noida This table has a composite primary key i.e. customer id, store id. The non key attribute is location. In this case location depends on store id, which is part of the primary key.
- 9. After decomposing it into second normal form it looks like: Table Purchase Customer_id Store_id 1 1 1 3 2 1 3 2 4 3 Table Store Store_id Location 1 Patna 2 Delhi 3 Noida
- 10. Third Normal Form (3NF) A table design is said to be in 3NF if both the following conditions hold: Table must be in 2NF Transitive functional dependency of non-prime attribute on any super key should be removed. An attribute that is not part of any candidate key is known as non-prime attribute. In other words 3NF can be explained like this: A table is in 3NF if it is in 2NF and for each functional dependency X-> Y at least one of the following conditions hold: X is a super key of table Y is a prime attribute of table An attribute that is a part of one of the candidate keys is known as prime attribute.
- 11. THIRD NORMAL FORM Table Book Details Bood_id Genre_id Genre type Price 1 1 Fiction 100 2 2 Sports 110 3 1 Fiction 120 4 3 Travel 130 5 2 sports 140 In the table, book_id determines genre_id and genre_id determines genre type. Therefore book_idd determines genre type via genre_id and we have transitive functional dependency.
- 12. After decomposing it into third normal form it looks like: TABLE BOOK Book_id Genre_id Price 1 1 100 2 2 110 3 1 120 4 3 130 5 2 140 TABLE GENRE Genre_id Genre type 1 Fiction 2 Sports 3 Travel
- 13. Boyce-Codd Normal Form (BCNF) It is an advance version of 3NF that’s why it is also referred as 3.5NF. BCNF is stricter than 3NF. A table complies with BCNF if it is in 3NF and for every functional dependency X->Y, X should be the super key of the table.
- 14. Boyce-Codd Normal Form Student Course Teacher Aman DBMS AYUSH Aditya DBMS RAJ Abhinav E-COMM RAHUL Aman E-COMM RAHUL abhinav DBMS RAJ KEY: {Student, Course} Functional dependency {student, course} -> Teacher Teacher-> Course Problem: teacher is not superkey but determines course.
- 15. After decomposing it into Boyce-Codd normal form it looks like: Student Course Aman DBMS Aditya DBMS Abhinav E-COMM Aman E-COMM Abhinav DBMS Course Teacher DBMS AYUSH DBMS RAJ E-COMM RAHUL
- 16. Fourth Normal Form (4NF) Fourth normal form (4NF) is a level of database normalization where there are no non-trivial multivalued dependencies other than a candidate key. It builds on the first three normal forms (1NF, 2NF and 3NF) and the Boyce- Codd Normal Form (BCNF). It states that, in addition to a database meeting the requirements of BCNF, it must not contain more than one multivalued dependency.
- 17. FOURTH NORMAL FORM Student Major Hobby Aman Management Football Aman Management Cricket Raj Management Football Raj Medical Football Ram Management Cricket Aditya Btech Football Abhinav Btech Cricket Key: {students, major, hobby} MVD: ->-> Major, hobby
- 18. After decomposing it into fourth normal form it looks like: Student Major Aman Management Raj Management Raj Medical Ram Management Aditya Btech Abhinav Btech Student Hobby Aman Football Aman Cricket Raj Football Ram Cricket Aditya Football Abhinav Cricket
- 19. Fifth Normal Form (5NF) A database is said to be in 5NF, if and only if, It's in 4NF. If we can decompose table further to eliminate redundancy and anomaly, and when we re-join the decomposed tables by means of candidate keys, we should not be losing the original data or any new record set should not arise. In simple words, joining two or more decomposed table should not lose records nor create new records.
- 20. FIFTH NORMAL FORM Seller Company Product Aman Coca cola company Thumps Up Aditya Unilever Ponds Aditya Unilever Axe Aditya Uniliver Lakme Abhinav P&G Vicks Abhinav Pepsico Pepsi Key: {seller, company, product} MVD: Seller ->-> Company, product Product is related to company.
- 21. After decomposing it into fifth normal form it looks like: Continued in next slide… Seller Product Aman Thumps Up Aditya Ponds Aditya Axe Aditya Lakme Abhinav Vicks Abhinav Pepsi Seller Company Aman Coca cola company Aditya Unilever Abhinav P&G Abhinav Pepsico
- 22. Company Product Coca cola company Thumps Up Unilever Ponds Unilever Axe Unilever Lakme Pepsico Pepsi P&G Vicks