Job simulation 2: repair a revenue join
A query runs without errors but overstates revenue. Review row grain, repair the join, and defend the denominator.
Existing companion · depth review pendingOpen collection →Read deeply.
Put your understanding to work.
Explore a topic as a collection of learning resources. Choose a chapter, work through a question, inspect the data or return to an explanation.
Explore the SQL reference collection →201 topic collections. Page 17 of 17. Existing companions are not automatically complete study units.
Job simulation 3: challenge an AI analysis
An assistant claims sales improved and identifies a best customer. Learn to separate calculation, unsupported inference and evidence.
Existing companion · depth review pendingOpen collection →Job simulation 4: defend your work in an interview
Turn a checked small analysis into a clear portfolio explanation without exaggerating its scope or impact.
Existing companion · depth review pendingOpen collection →Interview lab: top customers, ties and grain
Practise an analyst SQL question with explicit ranking rules and a follow-up that defeats a lucky answer.
Existing companion · depth review pendingOpen collection →Interview lab: explain an experiment without overclaiming
Calculate a treatment difference, diagnose missing design evidence and propose a responsible next check.
Existing companion · depth review pendingOpen collection →Interview lab: handle a late refund safely
Prepare a data engineering interview answer about historical metrics, idempotency and honest incident communication.
Existing companion · depth review pendingOpen collection →Interview lab: tell a truthful project story
Build a concise evidence-based answer, then practise follow-up questions about ownership and uncertainty.
Existing companion · depth review pendingOpen collection →Portfolio review: prove each claim
Review a weak project description against an evidence checklist, then rewrite it without inflated results.
Existing companion · depth review pendingOpen collection →Portfolio review: can another person reproduce it?
Turn an attractive project page into an inspectable analytical handoff with clear limits and practical next steps.
Existing companion · depth review pendingOpen collection →One useful next step
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