The correct answer is Third Normal Form (3NF) because the table contains a transitive dependency. In this scenario, CustomerEmail is functionally dependent on CustomerID, which is itself a non-key attribute, rather than depending directly on the primary key OrderID. This violates the 3NF rule that every non-key attribute must depend solely on the primary key, not on another non-key column. On the CompTIA Data+ DA0-001 exam, this concept tests your ability to recognize when a table is in 2NF but fails 3NF due to a transitive dependency—a common trap where test-takers mistakenly think the table is already normalized because it has no partial dependencies. A helpful memory tip: think of a transitive dependency as a “chain” where a non-key attribute depends on another non-key attribute, not the key itself—break the chain to reach 3NF.
DA0-001 Comparing and Contrasting Data Concepts Practice Question
This DA0-001 practice question tests your understanding of comparing and contrasting data concepts. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A table Orders has OrderID (primary key), CustomerID, and CustomerEmail. During analysis, it is found that CustomerID uniquely identifies CustomerEmail. Which normal form is violated if both CustomerID and CustomerEmail are stored in this table?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "primary"
Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
Why wrong: 2NF requires full functional dependency on the whole primary key. Since CustomerEmail does not depend on OrderID, it is not fully dependent, so it violates 2NF? Actually, 2NF violation occurs when a non-key attribute depends on part of a composite primary key. Here primary key is simple (OrderID), so 2NF is not violated. The correct violation is 3NF.
B
Third normal form (3NF)
CustomerEmail depends on CustomerID, which is a non-key attribute, creating a transitive dependency violating 3NF.
C
No violation
Why wrong: There is a clear transitive dependency.
D
First normal form (1NF)
Why wrong: 1NF is satisfied; attributes are atomic.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Third normal form (3NF)
The table violates Third Normal Form (3NF) because CustomerEmail is transitively dependent on CustomerID, which is not a candidate key. In 3NF, every non-key attribute must depend only on the primary key (OrderID), not on another non-key attribute. Since CustomerID uniquely identifies CustomerEmail, CustomerEmail depends on CustomerID, not directly on OrderID, creating a transitive dependency.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Second normal form (2NF)
Why it's wrong here
2NF requires full functional dependency on the whole primary key. Since CustomerEmail does not depend on OrderID, it is not fully dependent, so it violates 2NF? Actually, 2NF violation occurs when a non-key attribute depends on part of a composite primary key. Here primary key is simple (OrderID), so 2NF is not violated. The correct violation is 3NF.
✓
Third normal form (3NF)
Why this is correct
CustomerEmail depends on CustomerID, which is a non-key attribute, creating a transitive dependency violating 3NF.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
No violation
Why it's wrong here
There is a clear transitive dependency.
✗
First normal form (1NF)
Why it's wrong here
1NF is satisfied; attributes are atomic.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse transitive dependencies with partial dependencies, mistakenly thinking that because CustomerID is not part of the primary key, the violation is 2NF rather than 3NF.
Detailed technical explanation
How to think about this question
Under the hood, 3NF eliminates transitive dependencies where a non-key attribute (CustomerEmail) depends on another non-key attribute (CustomerID) rather than directly on the primary key. In a normalized schema, CustomerID and CustomerEmail should be moved to a separate Customers table, with CustomerID as a foreign key in Orders. A real-world scenario: if a customer changes their email, updating it in multiple orders without normalization could lead to update anomalies and data inconsistency.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the DA0-001 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Comparing and Contrasting Data Concepts — This question tests Comparing and Contrasting Data Concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Third normal form (3NF) — The table violates Third Normal Form (3NF) because CustomerEmail is transitively dependent on CustomerID, which is not a candidate key. In 3NF, every non-key attribute must depend only on the primary key (OrderID), not on another non-key attribute. Since CustomerID uniquely identifies CustomerEmail, CustomerEmail depends on CustomerID, not directly on OrderID, creating a transitive dependency.
What should I do if I get this DA0-001 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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