FC0-U71 Data and Database Fundamentals Practice Question
A database contains two tables: 'Authors' (AuthorID, Name) and 'Books' (BookID, Title, AuthorID). A query needs to return all authors and any books they have written, including authors with no books. Which type of JOIN should be used?
⚠ Common exam trap
The trap is choosing INNER JOIN because it is the most familiar, or RIGHT JOIN because it sounds like it preserves the 'right' (correct) table — candidates must map 'all authors including those with no books' to LEFT JOIN with Authors on the left.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
LEFT JOIN
A LEFT JOIN returns all rows from the left table (Authors) and matching rows from the right table (Books), filling NULLs where no match exists. Since the requirement is to include authors with no books, the Authors table must be the left (preserved) side. This is the textbook use case for LEFT JOIN.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
CROSS JOIN
Why it's wrong here
A CROSS JOIN produces the Cartesian product of both tables, pairing every author with every book regardless of AuthorID, so it cannot return authors matched to their own books nor preserve bookless authors. It is tempting because it does combine two tables, and it would be correct only when every possible row pairing is genuinely required.
- ✗
RIGHT JOIN
Why it's wrong here
A RIGHT JOIN returns every row from the Books table, so authors without books would be omitted, contradicting the requirement to include them. It is tempting because outer joins do preserve unmatched rows, and would be correct if the requirement were to list all books including those with no matching author.
- ✓
LEFT JOIN
Why this is correct
A LEFT JOIN returns every row from the left Authors table plus matching Books rows, filling NULLs where no match exists. That preserves authors with no books, exactly the inclusive requirement stated in the stem.
- ✗
INNER JOIN
Why it's wrong here
An INNER JOIN returns only rows with matching keys in both tables, so authors with no books would be excluded entirely. It is tempting because it is the default join for combining related records, and would be correct if only authors who have written at least one book were required.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
This FC0-U71 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-U71 exam.