Quick Answer
The correct answer is the JOIN clause, specifically an INNER JOIN, because it is the SQL mechanism designed to combine rows from two tables based on a related column, such as a foreign key linking Customers and Orders. When you need to pull customer names alongside their order details, a JOIN merges the tables into a single result set by matching values like CustomerID, which is exactly what the scenario requires. On the CompTIA ITF+ FC0-U61 exam, this question tests your understanding of relational database fundamentals, often appearing in a multiple-choice format where distractors like UNION or SELECT might tempt you—remember that UNION stacks rows vertically, while JOIN combines them horizontally. A common trap is confusing JOIN with WHERE clauses used for filtering, but the key is that JOIN is about linking tables, not narrowing results. To lock it in, think of the mnemonic “JOIN the dots on the foreign key” to recall that this clause connects related data across tables.
This FC0-U61 practice question tests your understanding of database fundamentals. 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 report requires data from two tables: Customers and Orders. Which SQL clause is used to combine rows from both tables based on a related column?
UNION
Why wrong: UNION combines result sets vertically, not based on relationships.
SUBQUERY
Why wrong: A subquery is nested inside another query; it does not combine tables in the same way.
JOIN
JOIN merges rows from tables based on a condition, typically a foreign key.
INTERSECT
Why wrong: INTERSECT returns common rows from two queries, not a join.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
JOIN
The JOIN clause (specifically an INNER JOIN) is used to combine rows from two or more tables based on a related column between them, such as a foreign key. In this scenario, the Customers and Orders tables would typically be linked by a CustomerID column, and a JOIN allows you to retrieve data like customer names alongside their order details in a single result set.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
UNION
Why it's wrong here
UNION combines result sets vertically, not based on relationships.
SUBQUERY
Why it's wrong here
A subquery is nested inside another query; it does not combine tables in the same way.
JOIN
Why this is correct
JOIN merges rows from tables based on a condition, typically a foreign key.
Related concept
Read the scenario before looking for a memorised answer.
INTERSECT
Why it's wrong here
INTERSECT returns common rows from two queries, not a join.
Common exam traps
Cisco often tests the distinction between set operations (UNION, INTERSECT) and join operations, so the trap here is that candidates confuse UNION (which stacks rows) with JOIN (which combines columns from related tables).
Detailed technical explanation
Under the hood, a JOIN works by creating a Cartesian product of the two tables and then filtering rows where the join condition (e.g., Customers.CustomerID = Orders.CustomerID) is true; the database optimizer may use indexes on the foreign key columns to avoid scanning all combinations. A subtle behavior is that an INNER JOIN excludes rows from either table that have no matching row in the other, whereas a LEFT JOIN would retain all rows from the Customers table even if no orders exist. In a real-world e-commerce system, a JOIN is essential for generating invoices that combine customer shipping addresses with their order line items.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the FC0-U61 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
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FAQ
Database Fundamentals — This question tests Database Fundamentals — Read the scenario before looking for a memorised answer..
The correct answer is: JOIN — The JOIN clause (specifically an INNER JOIN) is used to combine rows from two or more tables based on a related column between them, such as a foreign key. In this scenario, the Customers and Orders tables would typically be linked by a CustomerID column, and a JOIN allows you to retrieve data like customer names alongside their order details in a single result set.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
This FC0-U61 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 FC0-U61 exam.
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