DataBase Normalization 3NF

DB Normalization is the process of organizing the columns and fields of a relational table to minimize the redundancy,complexity and dependency.


First Normalization Form( 1NF ) :


A table is said to be in  1nf when there are no repeating groups or  no repeating elements present.


Second Normalization Form ( 2NF):


A table is in 2NF if 


 a) the table satisfies the 1NF


 b) no partial dependencies on the primary key(may be compound primary key) [ remove subsets of data that apply to multiple rows of a table and place them in separate tables supplied with foreign key relation ]




Third Normalization Form(3NF)


A table is in 3NF if


a)already satisfied the 2NF 

b) all the attributes should be directly dependent on the primary key

Example:

Let's try  normalizing the following table

1nf :remove the attributes which are redundant class_1,class_2,class_3 in the above table and bring it on as below

 

2nf: No partial dependency of non-key attributes on the primary key and remove subsets of data consolidated as tables with foreign key relation

Considering student_id and Mentor as compound primary key, class is not a full dependent on the composite py key and on segregating will result in the tables as follows 

Add caption

3Nf : all the attributes should be directly dependent on the primary key

In the STUDENT_ID,MENTOR AND MENTOR_ROOM table mentor_room is no way dependent on the student_id  which is the py key so on consolidating 

Thanks for Reading.... cheers  :-) :-)