Second Normal Form (2NF) in DBMS Theory - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the sentence to define Second Normal Form (2NF).

DBMS Theory

A table is in Second Normal Form if it is in First Normal Form and every non-key attribute is fully [1] on the primary key.

Drag options to blanks, or click blank then click option'

Adependent

Bindependent

Cpartially dependent

Dredundant

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing full dependency with partial dependency.

Thinking 2NF applies only to tables with single-column keys.

Second Normal Form requires that all non-key attributes depend fully on the entire primary key, not just part of it.

2fill in blank

medium

Complete the sentence to explain when 2NF is applicable.

DBMS Theory

Second Normal Form applies only to tables with [1] primary keys.

Drag options to blanks, or click blank then click option'

Asingle-column

Bcomposite

Cforeign

Dunique

Attempts:

3 left

💡 Hint

Common Mistakes

Assuming 2NF applies to tables with single-column keys.

Confusing composite keys with foreign keys.

2NF is concerned with removing partial dependencies, which only occur when the primary key has multiple columns (composite key).

3fill in blank

hard

Fix the error in the statement about 2NF.

DBMS Theory

A table in 2NF can have [1] dependency of non-key attributes on part of the primary key.

Drag options to blanks, or click blank then click option'

Ano

Bfull

Cpartial

Dtransitive

Attempts:

3 left

💡 Hint

Common Mistakes

Thinking partial dependencies are allowed in 2NF.

Confusing transitive dependency with partial dependency.

2NF eliminates partial dependency, so no non-key attribute should depend on only part of the primary key.

4fill in blank

hard

Fill both blanks to complete the example of a partial dependency.

DBMS Theory

In a table with primary key (StudentID, CourseID), the attribute [1] depends only on [2].

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AStudentName

BCourseID

CStudentID

DGrade

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing CourseID as the attribute dependent on part of the key.

Confusing Grade as partially dependent.

StudentName depends only on StudentID, not on the full composite key (StudentID, CourseID), which is a partial dependency.

5fill in blank

hard

Fill all three blanks to write a correct statement about 2NF.

DBMS Theory

To convert a table to 2NF, remove [1] dependencies by creating [2] tables and linking them with [3] keys.

Drag options to blanks, or click blank then click option'

Apartial

Bforeign

Cnew

Dtransitive

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing transitive dependencies with partial dependencies.

Not understanding the role of foreign keys in normalization.

Removing partial dependencies involves creating new tables and linking them with foreign keys to achieve 2NF.

Practice

1. Which of the following best describes the Second Normal Form (2NF) in database normalization?

easy

A. It requires the table to have no duplicate rows.

B. It removes transitive dependencies.

C. It removes partial dependencies on a composite primary key.

D. It ensures all columns are atomic.

Solution

1. Step 1: Understand 2NF definition

   2NF requires that every non-key attribute is fully functionally dependent on the entire primary key, not just part of it.

2. Step 2: Compare options

   It removes partial dependencies on a composite primary key correctly states removal of partial dependencies on composite keys. Other options describe 1NF (atomic columns), uniqueness, or 3NF (transitive dependencies).

3. Final Answer:

   It removes partial dependencies on a composite primary key. -> Option C

4. Quick Check:

   2NF = Remove partial dependencies [OK]

Hint: 2NF removes partial dependencies on composite keys [OK]

Common Mistakes:

• Confusing 2NF with 1NF or 3NF
• Thinking 2NF removes transitive dependencies
• Believing 2NF applies to single-column keys only

2. Which of the following is the correct condition for a table to be in Second Normal Form (2NF)?

easy

A. Every non-key attribute must depend on the whole primary key.

B. All attributes must be unique.

C. There must be no transitive dependencies.

D. The table must have no repeating groups.

Solution

1. Step 1: Recall 2NF condition

   2NF requires that non-key attributes depend on the entire primary key, not just part of it.

2. Step 2: Analyze options

   Every non-key attribute must depend on the whole primary key matches this condition. The table must have no repeating groups describes 1NF, There must be no transitive dependencies describes 3NF, and All attributes must be unique is unrelated to normalization.

3. Final Answer:

   Every non-key attribute must depend on the whole primary key. -> Option A

4. Quick Check:

   2NF = Full dependency on primary key [OK]

Hint: Non-key attributes depend on entire key in 2NF [OK]

Common Mistakes:

• Mixing 2NF with 1NF or 3NF conditions
• Assuming uniqueness means 2NF
• Ignoring composite keys in dependency

3. Consider a table with columns StudentID, CourseID, and InstructorName. The primary key is a composite of StudentID and CourseID. If InstructorName depends only on CourseID, what is the normalization status of this table?

medium

A. The table is not in 2NF due to partial dependency.

B. The table is in 2NF.

C. The table is in 3NF.

D. The table violates 1NF.

Solution

1. Step 1: Identify dependencies

   InstructorName depends only on CourseID, which is part of the composite key (StudentID, CourseID).

2. Step 2: Check for partial dependency

   Since InstructorName depends on only part of the key, this is a partial dependency, violating 2NF.

3. Final Answer:

   The table is not in 2NF due to partial dependency. -> Option A

4. Quick Check:

   Partial dependency means not 2NF [OK]

Hint: Partial dependency on part of key breaks 2NF [OK]

Common Mistakes:

• Assuming table is 2NF because it has a composite key
• Confusing 2NF with 3NF
• Ignoring partial dependencies

4. A table has columns OrderID, ProductID, ProductName, and Quantity. The primary key is composite: (OrderID, ProductID). The ProductName depends only on ProductID. What is the error in this design regarding 2NF?

medium

A. There is a transitive dependency violating 2NF.

B. The primary key is not composite.

C. The table is already in 2NF.

D. There is a partial dependency violating 2NF.

Solution

1. Step 1: Identify dependency of ProductName

   ProductName depends only on ProductID, part of the composite key (OrderID, ProductID).

2. Step 2: Recognize partial dependency

   This partial dependency violates 2NF, which requires full dependency on the entire key.

3. Final Answer:

   There is a partial dependency violating 2NF. -> Option D

4. Quick Check:

   Partial dependency breaks 2NF [OK]

Hint: Partial dependency on part of composite key breaks 2NF [OK]

Common Mistakes:

• Confusing partial with transitive dependency
• Thinking primary key must be single column for 2NF
• Assuming table is normalized without checking dependencies

5. You have a table with columns EmployeeID, ProjectID, EmployeeName, and ProjectName. The primary key is composite: (EmployeeID, ProjectID). Both EmployeeName and ProjectName depend only on their respective single keys (EmployeeID and ProjectID). How should you redesign the tables to achieve 2NF?

hard

A. Keep one table but remove EmployeeName and ProjectName columns.

B. Split into three tables: Employee(EmployeeID, EmployeeName), Project(ProjectID, ProjectName), and Assignment(EmployeeID, ProjectID).

C. Add a new composite key including EmployeeName and ProjectName.

D. No changes needed; the table is already in 2NF.

Solution

1. Step 1: Identify partial dependencies

   EmployeeName depends only on EmployeeID, and ProjectName depends only on ProjectID, parts of the composite key.

2. Step 2: Normalize by splitting tables

   To remove partial dependencies, create separate tables for Employee and Project details, and a linking table for assignments.

3. Final Answer:

   Split into three tables: Employee(EmployeeID, EmployeeName), Project(ProjectID, ProjectName), and Assignment(EmployeeID, ProjectID). -> Option B

4. Quick Check:

   Separate tables remove partial dependencies [OK]

Hint: Split tables to remove partial dependencies for 2NF [OK]

Common Mistakes:

• Trying to keep all data in one table
• Adding composite keys incorrectly
• Ignoring partial dependencies on composite keys