DATA ANALYST FOUNDATIONS / MODULE 03: SQL
Fictional Northstar dataset. Keep work locally.
Engine/version: ______  Practice file: ______
1. Schema: state the grain and key of orders, order_items, channels and raw_orders.
2. Q1-Q4: record row counts, units, date bounds, missing fields and duplicate findings.
3. Q5-Q6: monthly completed counts, sales and AOV; channel HAVING threshold in cents.
4. Q7-Q9: joined grain, inflated totals, item reconciliation and zero-activity partner channel.
5. Q10-Q11: status matrix, six-row reporting grid and coverage assumption.
6. Q12-Q13: previous observed month, first-row NULL, zero-base behaviour and cumulative total.
7. Q14: completed metrics plus item issue count. Explain why the check does not redefine sales.
8. Disposable-copy test: change F001 to 15000 cents without changing items; predict and verify outputs. Restore the reference.
9. Evidence note: 120-180 words with scope, results, limitations and a next step.
10. Self-review: 0-2 each for schema/population, core queries, joins/checks, comparisons/reproducibility, communication.