An Example of Database Normalization (Cont.)

Fifth Normal Form (Cont.)
Assume that the tuples are formed based on the following scenario; Note that we have this scenario for explaining the 5NF, otherwise you will not see it properly. Now if I try to decompose this relation into two relations for minimizing redundant data, I will be having these two tables (Sequences are added for understanding joins only).


Now, if I need to rejoin these with natural join, this will be the result. See the highlighted one. It is the result of join dependency. It is a spurious tuple which is not valid.

In order to avoid it, in order to make the relations as 5NF relation, let’s introduce another relation:

Now, if we rejoin all three, we will not see any issue. Therefore, in order to minimize redundant data and make sure no join dependency, make sure relations are formed as 5NF relations.




      “Love is suffering. One side always loves more.    
      — Catherine Deneuve