The answer is that the customer_id 12345 already exists in the table, as the error message explicitly states 'Duplicate entry '12345' for key 'PRIMARY'. This occurs because a primary key constraint enforces uniqueness for each row in a table, so attempting to insert a record with a customer_id that already exists triggers a violation. On the CompTIA Data+ DA0-001 exam, this type of duplicate primary key error troubleshooting tests your understanding of data integrity constraints and how to interpret database error logs. A common trap is confusing this with data type or connection issues, but the error message itself is your clue—it directly names the duplicate value. For memory, remember that a primary key is like a Social Security number: no two people can share the same one, so any attempt to reuse it will fail with a duplicate entry error.
DA0-001 Communicating Data Insights Practice Question
This DA0-001 practice question tests your understanding of communicating data insights. 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.
Exhibit
Refer to the exhibit.
ERROR: Duplicate entry '12345' for key 'PRIMARY'
Query: INSERT INTO customers (customer_id, name, email) VALUES (12345, 'John Doe', 'jdoe@example.com');
Refer to the exhibit. A data analyst receives this error when running a data load script. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The customer_id 12345 already exists in the table
Option B is correct. The error message explicitly states 'Duplicate entry '12345' for key 'PRIMARY'', meaning a record with customer_id 12345 already exists in the table. Option A (email too long) would give a different error. Option C (null name) would not cause primary key violation. Option D (connection lost) would give a different error.
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.
✗
The email field is too long
Why it's wrong here
This would cause a different error, not a primary key violation.
✗
The database connection is lost
Why it's wrong here
Connection loss would give a different error message.
✓
The customer_id 12345 already exists in the table
Why this is correct
The error indicates duplicate primary key value.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The name field is null
Why it's wrong here
Null values in non-key fields do not cause primary key errors.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 DA0-001 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Communicating Data Insights — This question tests Communicating Data Insights — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The customer_id 12345 already exists in the table — Option B is correct. The error message explicitly states 'Duplicate entry '12345' for key 'PRIMARY'', meaning a record with customer_id 12345 already exists in the table. Option A (email too long) would give a different error. Option C (null name) would not cause primary key violation. Option D (connection lost) would give a different error.
What should I do if I get this DA0-001 question wrong?
Identify which DA0-001 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This DA0-001 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DA0-001 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.