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5 normal forms in relational database theory
This document discusses database normalization through five forms. It explains why normalization is important to minimize data redundancy and update anomalies. The five normalization forms are described as removing repeating groups (1st), partial dependencies (2nd), transitive dependencies (3rd), remaining anomalies from functional dependencies (4th), and multi-value dependencies (5th). Examples are provided to illustrate transforming an unnormalized database design into normalized forms through separating relations and removing dependencies between fields.
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5 normal forms in relational database theory
- 1. FIVE NORMAL FORMSIN RELATIONAL DATABASE THEORY - AIME
- 2. TODAY’s CONTENT Whywe have to learn database normalization Bad Relational Database Design – unnormalized 5 Normalization Forms Better Relational Database Design - normailized Conclusion
- 3. Why normalization? DatabaseDesign Minimize Data Redundancy from UPDATE ANOMALIES UPDATE ANOMALIES Insertion anomalies Deletion anomalies Modification anomalies
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- 12. Normalization Unnormalization form 1st normalization form 2nd normalization form 3rdnormalization form 4th normalization form 5th normalization form Remove repeating group Remove partial dependencies Remove transitive dependencies Remove remaining anomalies from functional dependencies Remove multi-value dependencies join dependencies
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- 14. Unnormalized Form to1st Normalized Form
- 15. 1st Normalized Formproblem Data Redundancy Might cause inconsistency problem
- 16. Move to 2ndNormalized Form Conditions It’s already in 1st normalized form All attributes have fully functional dependency with primary key, NOT partial dependency Get rid of Partial dependencies
- 17. Move to 2ndNormalized Form Partial Dependency Non-prime field(s) depends on one primary key Student_ID + Course_ID Firstname, Surname, Cum.GPA, Position_ID, Position, Scholarship, Course_ID, Course, Credit, Grade, Lecturer_ID, Lecturer Student_ID Firstname, Surname, Cum.GPA, Position_ID, Position, Scholarship Course_ID Course, Credit, Grade, Lecturer_ID, Lecturer Student_ID + Course_ID Grade PK PK PK: Primary Key FK: Foreign Key FK FK
- 18. 2nd Normalized Form Separate into relation tables... PK PK Student Relation Course Relation FK FK Student-Course Relation Table
- 19. Move to 3rdNormalized Form Conditions It’s already in 2nd normalized form Get rid of Transitive Dependency PK PK Student Relation Course Relation FK FK Student-Course Relation Table
- 20. Move to 3rdNormalized Form Transitive Dependency Other attributes, those are not a primary key, cannot define the value of other attributes PK Student Relation Non-PK
- 21. 3rd Normalized Form Separate into relation tables... PK PK Student Relation Course Relation FK FK Student-Course Relation FK PK Position Relation
- 22. 3rd Normalized Form Separate into relation tables... PK Student Relation FK FK Student-Course Relation FK PK Position Relation PK Course Relation FK PK Lecturer Relation
- 23. Move to 4thNormalized Form Conditions It’s in 3rd normalized form Get rid of multi-valued dependencies PK PK Student Relation Course Relation FK FK Student-Course Relation FK PK Position Relation FK PK Lecturer Relation
- 24. Move to 4thNormalized Form Conditions It’s in 3rd normalized form Get rid of multi-valued dependencies PK PK Student Relation Course Relation FK FK Student-Course Relation FK PK Position Relation FK PK Lecturer Relation Add Research for each lecturer
- 25. Move to 4thNormalized Form Multi-valued Dependencies AB; Lecturer_IDLecturer AC; Lecturer_IDResearch But B and C is independent A B C PK PK Lecturer Relation Lecturer-Research Relation
- 26. Final Form –4th Normalized Form PK PK Student Relation Course Relation FK FK Student-Course Relation FK PK Position Relation FK PK Lecturer Relation PK Lecturer-Research Relation
- 27. 5th Normalized Form Separate more relation and it’s able to join back without spurious tuple occurance No spurious tuple PK Position Relation PK Position Relation
- 28. Supurios Tuple Example ???? Spurioustuple exist!!
- 29. PK PK Student Relation Course Relation FKFK Student-Course Relation FK PK Position Relation FK PK Lecturer Relation PK Lecturer-Research Relation OLD version NEW version
- 30. Conclusion The purposeof normalization is to Reduce data redundacy Prevent data inconsistency Trade-off Performance The factors to be considered while normalization Single-valued vs Multivalued Dependencies Partial dependency Transitive dependency Functional dependency Multivalued dependency Key and non-Key field relationship