The correct answer is that a duplicate username was inserted into the USERS table. This is because MySQL error 1062, shown as "Duplicate entry 'admin' for key 'PRIMARY'," directly indicates a violation of the PRIMARY KEY constraint, meaning the username field, which serves as the primary key, already contains the value 'admin' and cannot accept a second identical entry. On the CISA exam, this scenario tests your understanding of database integrity controls and how application logs reveal underlying data issues rather than network or permission failures. A common trap is mistaking this error for a connectivity problem or a syntax error, but the key clue is the specific reference to a duplicate key. Remember: a primary key enforces uniqueness, so any duplicate entry will always trigger error 1062—think of it as the database saying "I already have that one."
CISA Practice Question: Information Systems Acquisition, Development and Implementation
This CISA practice question tests your understanding of information systems acquisition, development and implementation. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 2019-11-15 14:23:45,123 [main] com.example.App - Error processing record ID 1045
java.sql.SQLIntegrityConstraintViolationException: ORA-00001: unique constraint (USERS.UK_USERNAME) violated
at com.example.dao.UserDao.insert(UserDao.java:45)
... 8 more
```
Refer to the exhibit. An application log shows an error. What is the MOST likely cause of this error?
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.
Refer to the exhibit.
```
ERROR 2019-11-15 14:23:45,123 [main] com.example.App - Error processing record ID 1045
java.sql.SQLIntegrityConstraintViolationException: ORA-00001: unique constraint (USERS.UK_USERNAME) violated
at com.example.dao.UserDao.insert(UserDao.java:45)
... 8 more
```
A
The database server is offline
Why wrong: A connection error would appear, not a constraint violation.
B
The user does not have insert privileges
Why wrong: Privilege errors would be like ORA-01031.
C
The data type of the username field is incorrect
Why wrong: Data type mismatch would cause a different error.
D
A duplicate username was inserted into the USERS table
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A duplicate username was inserted into the USERS table
The error message 'Duplicate entry 'admin' for key 'PRIMARY'' indicates a violation of the PRIMARY KEY constraint on the USERS table. Since the username field is the primary key, inserting a second row with the same username (e.g., 'admin') causes MySQL to reject the INSERT operation with error code 1062. This is a unique constraint violation, not a connectivity or privilege issue.
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 database server is offline
Why it's wrong here
A connection error would appear, not a constraint violation.
✗
The user does not have insert privileges
Why it's wrong here
Privilege errors would be like ORA-01031.
✗
The data type of the username field is incorrect
Why it's wrong here
Data type mismatch would cause a different error.
✓
A duplicate username was inserted into the USERS table
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse a duplicate key error with a privilege or connectivity issue, but the specific error code 1062 and the phrase 'Duplicate entry' directly point to a unique constraint violation, not a server or permission problem.
Detailed technical explanation
How to think about this question
MySQL enforces PRIMARY KEY uniqueness using a B-tree index; when an INSERT attempts to add a duplicate value, the storage engine (e.g., InnoDB) checks the index before writing the row and returns error 1062. In a real-world scenario, this often occurs when application code fails to check for existing usernames before registration, or when a unique constraint is added to a column that already contains duplicates. The error code and message are standardized across MySQL versions, making them reliable for troubleshooting.
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 junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
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.
Information Systems Acquisition, Development and Implementation — This question tests Information Systems Acquisition, Development and Implementation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: A duplicate username was inserted into the USERS table — The error message 'Duplicate entry 'admin' for key 'PRIMARY'' indicates a violation of the PRIMARY KEY constraint on the USERS table. Since the username field is the primary key, inserting a second row with the same username (e.g., 'admin') causes MySQL to reject the INSERT operation with error code 1062. This is a unique constraint violation, not a connectivity or privilege issue.
What should I do if I get this CISA 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: "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.
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