Functional Dependency Basics Quiz

A functional dependency A → B indicates that for every unique value of attribute A, there is a corresponding unique value of attribute B. This means that knowing the value of A allows us to determine the value of B, establishing a direct relationship where A influences or dictates B's value.

In the relation Student(ID, Name, Email), the ID uniquely identifies each student, making it a primary key. Therefore, knowing the ID allows us to determine the corresponding Name. This establishes a functional dependency where the ID functionally determines the Name, indicating that for each ID, there is exactly one associated Name.

When StudentID uniquely determines both Major and GPA, it indicates that knowing a student's ID gives complete information about their major and GPA. This means we can express the relationship as StudentID leading to a combination of both attributes, reflecting their dependency on the StudentID.

A functional dependency X → Y is considered trivial when the set of attributes Y is a subset of the set of attributes X. This means that knowing X inherently provides information about Y, making the dependency redundant or self-evident, as Y cannot contain any information that isn't already included in X.

A candidate key is a set of one or more attributes that can uniquely identify each record in a database table. This means that no two tuples (rows) can have the same values for the attributes that make up the candidate key, ensuring data integrity and enabling efficient data retrieval.

In a database, a transitive dependency occurs when one attribute indirectly depends on another through a third attribute. Here, since CourseID determines the Instructor and the Instructor determines the Office, it follows that CourseID also determines the Office, establishing a transitive dependency: CourseID → Office.

A relation is in First Normal Form (1NF) when all attributes contain atomic values, meaning each attribute holds indivisible data. This ensures that each piece of information is unique and can be easily accessed, preventing redundancy and maintaining data integrity within the database structure.

A partial dependency occurs when a non-key attribute is reliant on only a portion of a composite primary key, rather than the entire key. This violates the principles of normalization, as it can lead to redundancy and anomalies in database design. Identifying such dependencies is crucial for creating efficient relational databases.

To achieve Second Normal Form (2NF), it is essential to eliminate partial dependencies, which occur when a non-key attribute is dependent on only a part of a composite primary key. By removing these dependencies, we ensure that all non-key attributes are fully functionally dependent on the entire primary key, thereby enhancing the database's integrity and reducing redundancy.

In the relation Book, the presence of a transitive dependency indicates that AuthorID determines AuthorName, which suggests that AuthorName is dependent on AuthorID rather than being directly related to the primary key. This violates normalization rules, as it can lead to redundancy and inconsistency in the database.

The closure of a set of attributes refers to all attributes that can be inferred or derived from the original set through functional dependencies. This means it includes every attribute that is functionally determined by the initial attributes, highlighting the relationships and dependencies within a database schema.

A primary key uniquely identifies each record in a database table, ensuring that all attributes in that table are functionally dependent on it. This means that the value of the primary key determines the values of all other attributes, maintaining data integrity and preventing redundancy within the dataset.