SQL to Find Operational Inefficiency

Describe a time when you used database queries or data modeling to uncover an operational inefficiency at Revolut. What metrics did you track?

For this hands-on exercise, use the provided Revolut merchant, payment-attempt, and support-case data to identify merchants with recurring payment failures and summarize associated operational metrics.

Output

1. Return one row per merchant with at least two payment attempts and a failure rate of at least 25%.
2. Include merchant_id, merchant_name, attempt_count, failed_attempt_count, failure_rate, and avg_resolution_hours.
3. Sort by failure_rate descending, then avg_resolution_hours descending with NULL values last, then merchant_id ascending.