SQL · interview question
If you wrote a test around joins, what should the test prove first?
Multiple choiceMediumchapter-11-curatedpremiumsqljoins
SELECT o.id, c.email
FROM orders o
JOIN customers c ON c.id = o.customer_id;Answer and explanation
Correct answer
C. That the rule behaves correctly at the boundary cases the lesson is trying to make explicit.
Why
Good tests make the design safer to change because they lock in the meaningful behavior rather than surface-level implementation details.
Test yourself on SQL
A free test with instant, explained results. No account needed.
More SQL questions
- If you wrote a test around schema thinking, what should the test prove first?
- What do interviewers usually hear as a strong signal when you discuss schema thinking well?
- Which naming or modeling choice is strongest for schema thinking?
- What is the healthiest performance judgment around indexes and access patterns?
- Which option treats joins as an engineering policy decision instead of a syntax trick?
- A senior interviewer asks for one tradeoff behind joins. What is the strongest follow-up?