Your deliverables
Create a one-page local case note containing the fictional question, metric contract, faulty and repaired queries, controls, two limitations and the corrected stakeholder note. No file upload is needed. This companion activity does not save course progress or award a credential.
A five-minute mock interview
Minute 1: clarify what revenue means. Minute 2: explain the one-to-many join defect. Minute 3: show 410 minus 35 equals 375 and explain the denominator. Minute 4: challenge the campaign claim. Minute 5: propose the smallest useful next check. Ask a partner to interrupt with “Why not DISTINCT?” and “Would February refunds change your answer?”
Reviewer rubric
Score five dimensions from 0 to 2: metric clarity, grain/correctness, reproducibility, uncertainty, communication. Zero means absent or incorrect; one means partly justified; two means explicit and checkable. A suggested self-practice target is 8/10 with no zero in correctness. This rubric is not a hiring assessment or proof of job readiness.
Role-specific follow-up
Analyst: write a 100-word recommendation without a causal claim. BI developer: specify dashboard labels, date filters and gross/net reconciliation. Data engineer: propose idempotent refund ingestion, uniqueness constraints and a late-arrival policy. ML practitioner: explain why six orders cannot support a credible predictive customer-value model. Select one role and justify your proposed check.
A truthful portfolio bullet
“Built a fictional SQLite revenue reconciliation case; corrected one-to-many refund join inflation, verified control totals and documented cutoff/denominator assumptions.” Do not describe the fictional EUR 60 error as money saved for an employer. Include the exact teaching source and your own extension, not another person’s project as yours.
Your next practice cycle
Rerun the case with the equal-price order and added refund from simulation 2. Explain what changed and why. Revisit SQL, statistics, data engineering and communication modules based on the rubric. Repeat this pattern with larger independently validated cases before drawing conclusions about readiness for a role.
Try the activity before reading its reference. Keep your sources, commands and assumptions with your work. Companion activities are unsaved self-practice and do not award a certificate or change lesson progress.