3-Day Rolling Sum of Sales

SQL coding challenge · Difficulty: easy · +100 XP

Problem

The analytics team tracks a 3-day rolling sum of sales so short-term spikes are smoothed out.

Tables

Table: daily_sales

| sale_date | sales |
| --- | --- |
| 2024-01-01 | 100 |
| 2024-01-02 | 200 |
| 2024-01-03 | 150 |
| 2024-01-04 | 300 |
| 2024-01-05 | 250 |
| 2024-01-06 | 180 |
| 2024-01-07 | 220 |
| 2024-01-08 | 90 |
| 2024-01-09 | 310 |

Expected Output

| sale_date | sales | rolling_3day_sum |
| --- | --- | --- |
| 2024-01-01 | 100 | 100 |
| 2024-01-02 | 200 | 300 |
| 2024-01-03 | 150 | 450 |
| 2024-01-04 | 300 | 650 |
| 2024-01-05 | 250 | 700 |
| 2024-01-06 | 180 | 730 |
| 2024-01-07 | 220 | 650 |
| 2024-01-08 | 90 | 490 |
| 2024-01-09 | 310 | 620 |

• Return: sale_date, sales, rolling_3day_sum
• Sort by sale_date ascending
• Function to use: SUM() OVER (ORDER BY sale_date ROWS BETWEEN 2 PRECEDING AND CURRENT ROW)