Normalization ( 2 NF)
We talked about 1NF in the previous post.
We need to understand Functional Dependencies first.
There are many Rons across many departments. That’s why Name and Dept together can form a Primary Key here. Key attributes are Name & Dept. Age and Dept Head are non-key attributes.
Functional Dependency :
{ Name ,Dept } ⤍ Age
Just Name or Dept is not enough to determine age. Together Name & Dept determines one definite value of Age. That’s functional dependency.
Age is dependent on the entire key.
2 NF Rule: Data is already on 1 NF form and additionally, all non key attributes must be functionally dependent on entire key (not partial key).
{ Dept } ⤍ Dept Head
Dept Head is not dependent on the entire key, but only partial key. That’s a violation of 2 NF form.
What could bring it into 2 NF form?
{ Name, Dept } ⤍ age
{ Dept } ⤍ Dept Head
Now all non-key attributes depend on entire key attributes.
This complies with 2 NF form.
Writer: Piyush Kulkarni
