Understanding Functional Dependencies for Database Normalization

Last update on September 20 2025 13:31:24 (UTC/GMT +8 hours)

Identifying Functional Dependencies in a Table

Write a SQL query to identify functional dependencies in a table.

Solution:

-- Analyze functional dependencies in the Employees table.
SELECT DISTINCT DepartmentID, DepartmentName
FROM Employees;

-- Verify that DepartmentName depends only on DepartmentID.

Explanation:

Purpose of the Query :

The goal is to identify functional dependencies to guide normalization efforts.

Key Components :

DISTINCT: Ensures that each department name corresponds to a unique department ID.
Verifies that DepartmentName depends only on DepartmentID.

Why Identify Functional Dependencies? :

Functional dependencies reveal how attributes relate to each other, helping to achieve higher normal forms.
They guide decisions about splitting tables and reducing redundancy.

Real-World Application :

In HR systems, identifying dependencies ensures that department details are stored consistently.

Notes:

Functional dependencies are the foundation of normalization.
Use them to determine candidate keys and eliminate redundancies.
Important Considerations:

Document all dependencies before designing the database schema.

For more Practice: Solve these Related Problems:

Write a SQL query to identify functional dependencies in a table storing customer orders and shipping addresses.
Write a SQL query to analyze functional dependencies in a table containing product categories and subcategories.
Write a SQL query to determine if employee roles depend solely on their department in a given table.
Write a SQL query to verify functional dependencies between supplier IDs and supplier locations in a procurement table.

Go to:

PREV : Designing a Composite Key for Multi-Attribute Relationships.
NEXT : Designing a Recursive Relationship for Hierarchical Data.

Have another way to solve this solution? Contribute your code (and comments) through Disqus.