DS0-001 Data Querying And Analysis Practice Question
When joining two tables in SQL where you need to return all records from the left table even if there is no match in the right table, which JOIN type is appropriate?
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 and the matched rows from the right table, filling with NULL if no match exists.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
LEFT JOIN
Why this is correct
LEFT JOIN preserves all data from the primary table.
- ✗
CROSS JOIN
Why it's wrong here
CROSS JOIN creates a Cartesian product.
- ✗
INNER JOIN
Why it's wrong here
INNER JOIN only returns rows with matches in both tables.
- ✗
FULL OUTER JOIN
Why it's wrong here
FULL OUTER JOIN returns all rows from both tables, not just the left.
About these practice questions
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official CompTIA exam blueprint
This DS0-001 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 DS0-001 exam.