Canonical cover in DBMS Theory - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a canonical cover in database theory?

A canonical cover is a simplified set of functional dependencies that is equivalent to the original set but has no redundant dependencies or attributes.

beginner

Why do we use a canonical cover?

We use a canonical cover to make the set of functional dependencies easier to work with by removing redundancies, which helps in database normalization and design.

intermediate

What are the main steps to find a canonical cover?

1. Split dependencies with multiple attributes on the right side into single attributes.<br>2. Remove extraneous attributes from left and right sides.<br>3. Remove redundant dependencies.

intermediate

What does it mean to remove an extraneous attribute?

Removing an extraneous attribute means eliminating an attribute from a functional dependency if it can be inferred from other dependencies without changing the overall meaning.

beginner

How does a canonical cover help in database normalization?

A canonical cover helps by providing a minimal and clear set of dependencies, making it easier to identify keys and design tables that avoid redundancy and update anomalies.

What is the first step in finding a canonical cover?

A Removing extraneous attributes from the left side

B Removing redundant dependencies

C Splitting dependencies with multiple attributes on the right side

D Combining all dependencies into one

The first step is to split dependencies that have multiple attributes on the right side into separate dependencies with single attributes.

Which of the following is NOT a goal of a canonical cover?

A Add more dependencies for clarity

B Remove redundant dependencies

C Remove extraneous attributes

D Simplify the set of functional dependencies

A canonical cover aims to simplify and reduce dependencies, not add more.

What does it mean if an attribute is extraneous in a functional dependency?

A It can be removed without changing the dependency's meaning

B It is a key attribute

C It is the only attribute on the right side

D It is necessary for the dependency

An extraneous attribute can be removed without affecting the overall set of dependencies.

Why is a canonical cover important for database normalization?

A It merges all tables into one

B It increases the number of tables

C It removes all functional dependencies

D It helps identify keys and avoid redundancy

A canonical cover helps identify keys and design tables that avoid redundancy and anomalies.

Which step comes after removing extraneous attributes when finding a canonical cover?

A Splitting dependencies

B Removing redundant dependencies

C Adding new dependencies

D Normalizing tables

After removing extraneous attributes, the next step is to remove redundant dependencies.

Explain what a canonical cover is and why it is useful in database design.

Think about how simplifying dependencies helps organize data better.

Describe the main steps involved in finding a canonical cover from a set of functional dependencies.

Consider the process of making dependencies minimal and clear.