Pretty clear what they wanted once I saw the table structure.
Start by clarifying the schema and assumptions (e.g., transaction date column, vendor identifier, amount column, and whether 'last 2 years' is relative to current date or a fixed period). Then write a SQL query that filters transactions to the last 2 years, groups by vendor, sums the amount, orders descending, and limits to 3. Finally, discuss edge cases like refunds, nulls, and time zone considerations.
Pro tip: Mention that you would confirm the definition of 'last 2 years' with the stakeholder—whether it's a rolling 24-month window or calendar years—and consider using a date filter that is sargable (e.g., `transaction_date >= DATEADD(year, -2, CURRENT_DATE)`) to leverage indexes.
Ask about the table structure: column names for vendor, amount, and transaction date. Confirm the definition of 'last 2 years' (rolling vs. calendar) and whether to include refunds or negative amounts.
Apply a WHERE clause to restrict transactions to the last 2 years. Use a dynamic date function if the query should always reflect the current date, or hardcode dates if a fixed period is needed.
Use GROUP BY vendor and SUM(amount) to calculate total charged per vendor. Consider handling NULLs and negative amounts appropriately.
Order the results by total amount descending and use LIMIT 3 (or TOP 3 depending on SQL dialect) to get the top vendors.
Mention potential issues like ties, missing data, or time zone differences. Suggest adding a tie-breaker (e.g., vendor name) if needed for deterministic results.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.