SQL: Average Order Value by Month (DATE_TRUNC)

MediumDatabases

Description

> This problem is paper-only - see explanation for the canonical SQL solution. Given `Orders(id, order_date, total)` where `order_date` is an ISO date string, return the **average order value per calendar month** rounded to 2 decimals. Sort by month ascending. **For the auto-grader:** return `[{ month, avg_total }]` where `month` is `"YYYY-MM"`.

Example 1

Input: orders = [{id:1,order_date:"2026-01-15",total:100},{id:2,order_date:"2026-01-20",total:200},{id:3,order_date:"2026-02-01",total:50}]

Output: [{month:"2026-01",avg_total:150},{month:"2026-02",avg_total:50}]

Constraints

- 0 <= orders.length <= 10^4 - order_date is "YYYY-MM-DD" - avg_total rounded with banker's-rounding-not-required half-away-from-zero (use Math.round / round() in tests).

Loading editor...