Explain the concept of functional dependency in database normalization.

Functional dependency is a fundamental concept in database normalization that helps in organizing and structuring data efficiently. It refers to the relationship between attributes or columns in a database table.

In simple terms, functional dependency occurs when the value of one attribute determines the value of another attribute in the same table. This means that if we know the value of one attribute, we can determine the value of another attribute without any ambiguity.

There are two types of functional dependencies: full functional dependency and partial functional dependency.

1. Full Functional Dependency: In this type, the value of one attribute uniquely determines the value of another attribute. It means that if we have a composite key (a combination of multiple attributes), removing any attribute from the key will result in losing the functional dependency. For example, if we have a table with attributes A, B, and C, and A determines B and C, then A is the full functional dependency.

2. Partial Functional Dependency: In this type, the value of one attribute determines the value of another attribute, but removing any attribute from the key will not result in losing the functional dependency. It means that the functional dependency exists even if we remove some attributes from the key. For example, if we have a table with attributes A, B, and C, and A determines B, but C is dependent on both A and B, then A is the partial functional dependency.

Functional dependency plays a crucial role in database normalization as it helps in eliminating data redundancy and anomalies. By identifying and establishing functional dependencies, we can break down a table into multiple smaller tables, each containing a single theme or concept. This process, known as normalization, helps in reducing data redundancy, improving data integrity, and simplifying data management.

Overall, functional dependency is a key concept in database normalization that ensures data consistency and efficiency by establishing relationships between attributes in a table.