Functional dependency definition in DBMS Theory - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Functional Dependency

Which of the following best describes a functional dependency in a database?

A A process of normalizing data to reduce redundancy.

B A rule that allows multiple values for a single attribute in a table.

C A constraint that enforces referential integrity between tables.

D A relationship where one attribute uniquely determines another attribute.

💡 Hint

Think about how one piece of data can determine another in a table.

A functional dependency means that if you know the value of one attribute (or set of attributes), you can find exactly one value of another attribute. This is key in database design.

📋 Factual

intermediate

Identifying Functional Dependency Notation

In the notation A → B, what does this represent in terms of functional dependency?

A Attribute B functionally determines attribute A.

B Attributes A and B are independent of each other.

C Attribute A functionally determines attribute B.

D Attributes A and B are both primary keys.

💡 Hint

Look at the arrow direction carefully.

The arrow points from the determinant to the dependent attribute. So, A → B means A determines B.

🚀 Application

advanced

Applying Functional Dependency in a Table

Given a table with columns StudentID, StudentName, and Major, which functional dependency is correct?

A StudentID → StudentName

B StudentName → Major

C Major → StudentID

D StudentName → StudentID

💡 Hint

Consider which attribute uniquely identifies a student.

StudentID uniquely identifies a student, so it determines the StudentName. The reverse is not necessarily true because names can repeat.

🔍 Analysis

advanced

Analyzing Functional Dependency Impact

What is the impact of violating a functional dependency in a database table?

A It ensures data is always normalized.

B It causes data redundancy and inconsistency.

C It allows multiple primary keys in a table.

D It improves query performance.

💡 Hint

Think about what happens when one attribute does not uniquely determine another.

Violating functional dependency can lead to duplicate or conflicting data, causing redundancy and inconsistency.

❓ Reasoning

expert

Determining Functional Dependency from Data

Consider the following data in a table:

EmployeeID | Department
1          | Sales
2          | Sales
3          | HR
4          | HR
5          | Sales

Which functional dependency is true based on this data?

A EmployeeID → Department

B Department → EmployeeID

C EmployeeID and Department are independent

D Department uniquely determines EmployeeID

💡 Hint

Check if one attribute value always leads to exactly one value of the other.

Each EmployeeID corresponds to exactly one Department, so EmployeeID determines Department. But one Department has many EmployeeIDs, so Department does not determine EmployeeID.