Fifth Normal Form (5NF)
These relations still have a difficulty. While defining the 4NF we mentioned that all the attributes depend upon each other. Whereas creating the two tables in the 4NF, although we have preserved the dependencies among Vendor Code and Item code in the first table and Vendor Code and Item code in the second table, we have lost the relationship among Item Code and Project No. If there were a primary key then this loss of dependency would not have happened..