First Normal Form (1NF) in DBMS Theory - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define First Normal Form (1NF) in database normalization.

DBMS Theory

1NF requires that each column in a table contains [1] values only.

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

Aduplicate

Bmultiple

Catomic

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Thinking 1NF allows multiple values in a single column.

Confusing 1NF with higher normal forms.

First Normal Form (1NF) means each column must have atomic (indivisible) values, no sets or lists.

2fill in blank

medium

Complete the statement about 1NF regarding table structure.

DBMS Theory

A table is in 1NF if it has no [1] groups or arrays in any column.

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

Aredundant

Bindexed

Cempty

Dnested

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing nested groups with empty or redundant data.

Thinking indexes affect 1NF.

1NF requires no nested groups or arrays in columns; each field must be atomic.

3fill in blank

hard

Fix the error in the definition of 1NF.

DBMS Theory

1NF means each column can have [1] values, including lists or sets.

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

Aatomic

Bduplicate

Cnull

Dmultiple

Attempts:

3 left

💡 Hint

Common Mistakes

Believing 1NF allows lists or sets in columns.

Mixing 1NF rules with those of higher normal forms.

The error is that 1NF does NOT allow multiple values like lists or sets; it requires atomic values.

4fill in blank

hard

Fill both blanks to complete the 1NF condition for table columns.

DBMS Theory

Each column must contain [1] values and must not have [2] groups.

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

Aatomic

Bnull

Crepeating

Dindexed

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing null or indexed instead of repeating groups.

Confusing atomic with null values.

1NF requires atomic values and no repeating groups in columns.

5fill in blank

hard

Fill all three blanks to describe the 1NF rule for table columns.

DBMS Theory

In 1NF, each column must have [1] values, no [2] groups, and each record must be uniquely [3].

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

Aatomic

Brepeating

Cidentified

Dindexed

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing indexed with identified.

Thinking repeating groups are allowed.

1NF requires atomic values, no repeating groups, and unique identification of records.

Practice

1. What does First Normal Form (1NF) primarily ensure in a database table?

easy

A. Tables have multiple primary keys

B. Tables have no foreign keys

C. Each cell contains only one atomic value

D. Data is encrypted for security

Solution

1. Step 1: Understand the definition of 1NF

   1NF requires that each column in a table holds atomic (indivisible) values, meaning no multiple values or lists in a single cell.

2. Step 2: Compare options with 1NF definition

   Only Each cell contains only one atomic value matches this requirement. Other options relate to different concepts like keys or security.

3. Final Answer:

   Each cell contains only one atomic value -> Option C

4. Quick Check:

   1NF = atomic values only [OK]

Hint: 1NF means no multiple values in one cell [OK]

Common Mistakes:

• Confusing 1NF with encryption or keys
• Thinking 1NF allows multiple values in a cell
• Mixing 1NF with higher normal forms

2. Which of the following table structures violates First Normal Form (1NF)?

easy

A. A table with a column storing multiple phone numbers separated by commas

B. A table where each column contains only single values

C. A table with unique primary keys for each row

D. A table with no repeating rows

Solution

1. Step 1: Identify the 1NF violation

   1NF forbids multiple values in a single cell. Storing multiple phone numbers separated by commas means one cell holds multiple values.

2. Step 2: Check other options

   Options B, C, and D follow 1NF rules because they have atomic values and unique rows.

3. Final Answer:

   A table with a column storing multiple phone numbers separated by commas -> Option A

4. Quick Check:

   Multiple values in one cell violate 1NF [OK]

Hint: Look for columns with multiple values in one cell [OK]

Common Mistakes:

• Assuming commas separate values correctly in 1NF
• Confusing unique rows with atomic values
• Ignoring multi-valued columns

3. Consider this table data:
StudentID | Courses
1 | Math, Science
2 | English
3 | Math, English
Which statement is true about this table regarding 1NF?

medium

A. The table violates 1NF because the Courses column has multiple values

B. The table is in 1NF because Courses are listed as text

C. The table is in 1NF because each row has a unique StudentID

D. The table violates 1NF because StudentID is not unique

Solution

1. Step 1: Analyze the Courses column

   The Courses column contains multiple values separated by commas in some rows, which means cells are not atomic.

2. Step 2: Check uniqueness and 1NF rules

   Although StudentID is unique, 1NF requires atomic values in each cell. Multiple courses in one cell violate 1NF.

3. Final Answer:

   The table violates 1NF because the Courses column has multiple values -> Option A

4. Quick Check:

   Multiple values in one cell break 1NF [OK]

Hint: Check if any cell holds multiple values separated by commas [OK]

Common Mistakes:

• Thinking unique keys alone satisfy 1NF
• Ignoring multi-valued columns
• Assuming text format means atomic values

4. You have a table with columns: OrderID, ProductIDs where ProductIDs stores multiple product IDs separated by semicolons. How would you fix this to comply with 1NF?

medium

A. Remove the ProductIDs column entirely

B. Keep the table as is because semicolons separate values

C. Combine all ProductIDs into one string without separators

D. Split the table so each row has one ProductID per OrderID

Solution

1. Step 1: Identify the 1NF violation

   Storing multiple product IDs in one cell violates 1NF because values are not atomic.

2. Step 2: Apply 1NF correction

   Splitting the table so each row has one ProductID per OrderID ensures atomic values and removes repeating groups.

3. Final Answer:

   Split the table so each row has one ProductID per OrderID -> Option D

4. Quick Check:

   One value per cell fixes 1NF violation [OK]

Hint: Make each cell hold only one value by splitting rows [OK]

Common Mistakes:

• Thinking separators alone satisfy 1NF
• Removing columns instead of fixing data structure
• Combining values into one string without atomicity

5. A table stores employee skills as follows:
EmpID | Skills
101 | Java, Python
102 | Python
103 | Java, SQL, Python
How can you transform this table into 1NF compliant form?

hard

A. Keep skills as comma-separated values in one cell

B. Create a new row for each skill per EmpID

C. Remove the Skills column and store skills elsewhere

D. Combine all skills into a single string without commas

Solution

1. Step 1: Identify multi-valued attribute

   The Skills column contains multiple skills separated by commas, violating 1NF.

2. Step 2: Normalize by creating multiple rows

   To comply with 1NF, create a separate row for each skill linked to the same EmpID, making each cell atomic.

3. Final Answer:

   Create a new row for each skill per EmpID -> Option B

4. Quick Check:

   One skill per row ensures 1NF compliance [OK]

Hint: Turn multi-valued cells into multiple rows [OK]

Common Mistakes:

• Leaving multi-valued cells unchanged
• Removing data instead of restructuring
• Combining values without atomicity