SIXTH NORMAL FORM MARYLIN MVULA B190637B Normalisation:6NF • A relation is in 6NF, only if it is in 5NF and every join dependency on the relation is trivial. • It was created to handle situation where temporal data vary independently to avoid unnecessary duplication • 6NF decompose the relation variables into irreducible components. • Sixth Normal Form has been referred Domain-Key Noraml Form to by other authors • The 6NF is currently being used in some data warehouses where the advantages outweighs the disadvantages. Example • The table below shows Student Marks • Here the table is in 5NF because each join dependency is implied by the unique candidate key of the table which is Student_Id Student_LNa me Alter Marks S01 Student_FNa me Tom S02 Jacob Waston 80 S03 Harry Smith 85 Student_ID 90 CONT.. StudentFirstName Student_ID Student_FName S01 Tom S02 Jacob S03 Harry CONT.. StudentLastName Student_ID Student_LName S01 Alter S02 Waston S03 Smith CONT.. StudentResult Student_ID Marks S01 90 S02 S03 80 85 Example 2 Student Table Roll_No Department Grade 2 Computer Science B 3 Mechanics A 4 Physics C CONT.. Student Details Roll_No Department 2 Computer Science 3 Mechanics 4 Physics CONT.. Student Results Roll_No Grade 2 B 3 A 4 C
