Filtering
Which query keeps only rows with status = 'open'?
Short check · explained answers
SQL Skills Test
Six practical tasks covering Filtering, Aggregation, Table joins. Choose a solution and get an explanation for every answer.
6questions
5minutes
3topics
free
✓ No sign-up · instant explained result
01
What the tasks cover
Choose a solution rather than rate yourself. Check the supplied data and compare three alternatives in every case.
Aggregation
Four rows exist; three have non-NULL email. What does COUNT(email) return?
Table joins
Keep every customer, including those without orders. Which join fits?
02
Three topics to review
Two tasks per topic help you choose where to start revising.
Filtering
Which query keeps only rows with status = 'open'? How do you find rows where manager_id is NULL?
Aggregation
Four rows exist; three have non-NULL email. What does COUNT(email) return? Which query counts orders for each customer?
Table joins
Keep every customer, including those without orders. Which join fits? The only customers are 7 and 8, with two orders and one respectively; there are no other orders. How many rows does INNER JOIN on customer_id return?
How the result is calculated
Each correct answer earns one point: six overall and two per topic. The percentage is accuracy on this set. Five minutes is an estimate; there is no timer or speed bonus.
- 1Read the condition and select one answer.
- 2Complete six tasks; go back when needed.
- 3Open your result and every explained answer.
How to approach the tasks
- Read the complete condition, including limits and table data.
- Compare all alternatives, not just the first familiar one.
- Review your choices before finishing; read the explanations afterwards.
FAQ
SQL Skills Test — FAQ
This short BrainApps test checks how you apply knowledge to concrete tasks. It covers three topics: Filtering, Aggregation, Table joins, with two questions each. One example is: “Which query keeps only rows with status = 'open'?”. Choose one of three answers; you can revisit questions and change choices before finishing. The result shows your correct-answer total, topic scores and a full review: your choice, the correct answer and its explanation. Use it for independent preparation or a team discussion. Start with a topic where you made an error, explain the rule in your own words and then repeat the check.
Which topics does this test cover?+
Three sections: Filtering, Aggregation, Table joins. Two questions each make six tasks overall.
What does a task look like?+
For example: “Which query keeps only rows with status = 'open'?”. Choose one of three alternatives using the supplied information.
What do the points mean?+
One point per correct answer, up to six. Each topic shows correct choices out of two. Explanations help identify the reason for an error.
Can I revisit my answers?+
Yes, switch questions and change choices before finishing. The result stores your final answer.
Do I need an account?+
No. The test and result are available without an account; keep the result link. You can register for further training.
How can I use the review to prepare?+
Explain why the correct choice fits, then compare it with your own. In a team, discuss which data determined the decision.
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