In 6NF, the relation variable is decomposed into irreducible components. A relation is in 6NF, only if, It is in 5NF, and every join dependency on the relation is trivial
Let us see an example −
<Student>
| Enrollment_No | Name | Marks |
The possible join dependencies for the above would be −
| {Enrollment_No, Marks} {Enrollment_No, Name} |
In Sixth Normal Form (6NF), it would be decomposed to −
<StudentInformation>
| Enrollment_No | Name |
<ResultInformation>
| Enrollment_No | Marks |
Let us see another example −
<StudentMarks>
| Student_ID | Student_FirstName | Student_LastName | Marks |
| S01 | Tom | Alter | 90 |
| S02 | Jacob | Watson | 80 |
| S03 | Harry | Smith | 85 |
Let us decompose the table −
<StudentFirstName>
| Student_ID | Student_FirstName |
| S01 | Tom |
| S02 | Jacob |
| S03 | Harry |
<StudentLastName>
| Student_ID | Student_LastName |
| S01 | Alter |
| S02 | Watson |
| S03 | Smith |
<StudentResult>
| Student_ID | Marks |
| S01 | 90 |
| S02 | 80 |
| S03 | 85 |
Now the above tables are in 6NF, but as you can guess on your know that this isn’t possible in real-world.