Contents:

1. Functional Dependency
2. Anomalies
3. Normalizaton

Diagramming Tool

Functional Dependency

We all know about Entity relationships. It is the relationship between Models / Entities / Classes. Similarly, Functional Dependency is the relationship between attributes.

Suppose we have a Table called Student. The Student has the following attributes.

1. student_id - Primary key
2. student_name
3. student_age

If we ask, please tell me the name associated with <some> student_id, we can easily answer, as the student id is unique and there will always be a unique student id associated with a student name.

But if we ask, please give me the student_id associated with <some> name, we would not be able to successfully identify a single id associated with that name. This is because, name is not uniquely identifiable property and there can be ‘n’ number of id’s associated with the same name.

Here, we can say, student_id uniquely identifies student _name

OR

student_id determines student _name.

OR

student_id → student _name.

Trivial and Non Trivial Functional Depencency