AnalystOS Mission / SQL
Fix a Broken Query
Fix a broken SQL query and explain what was wrong in plain language.
Difficulty
Intermediate
Estimated time
45-70 minutes
Reward
+100 XP
Role fit
Data Analyst / Data Scientist
Mission Brief
What you need to solve
Fix a broken SQL query and explain what was wrong in plain language.
Best fit
Data Analyst
Best fit
Data Scientist
Data You Will Use
What information you get
Subscription cohorts with signup dates, invoices, onboarding bands, churn flags, retained revenue, and risk scores.
Guided Steps
Follow Step 1 to Step 5
Use these beginner-friendly steps before you accept the mission.
Find why the query is wrong.
Fix the filter, grouping, join, or calculation.
Check that the answer matches the question.
Explain the fix in simple words.
Save your work and explain your answer in simple language.
What You Will Create
What your work should contain
A fixed answer, what changed, a quick check, and a short business summary.
Fixed query
What was wrong
Check notes
Business summary
Starter Question
Use this to begin
Fix the query and show that the corrected answer can help a business decision.