Kings of the Calendar

A hard SQL interview practice problem on DataDriven. Write and execute real sql code with instant grading.

Domain

SQL

Difficulty

hard

Seniority

L4

Problem

We publish a monthly leaderboard of the best-selling products for an online marketplace, where selling is measured by total units sold in each calendar month. For every month, return the top 10 products with their total units sold and standing, counting only completed sales by dropping any transaction with a negative `total_amount` (those are refunds), with the oldest month first.

Summary

Every month has a winner.

Practice This Problem

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