7-Day Rolling Sales by Product Category

SQL coding challenge · Difficulty: medium · +150 XP

Problem

For each row show a 7-day (7-row) rolling sum of sales per product category.

Tables

Table: category_sales

| category | sale_date | sales |
| --- | --- | --- |
| Books | 2024-01-01 | 40 |
| Books | 2024-01-02 | 60 |
| Books | 2024-01-03 | 80 |
| Books | 2024-01-04 | 20 |
| Books | 2024-01-05 | 100 |
| Books | 2024-01-06 | 50 |
| Books | 2024-01-07 | 70 |
| Books | 2024-01-08 | 30 |
| Toys | 2024-01-01 | 200 |
| Toys | 2024-01-02 | 150 |
| Toys | 2024-01-03 | 100 |

Expected Output

| category | sale_date | sales | rolling_7day_sum |
| --- | --- | --- | --- |
| Books | 2024-01-01 | 40 | 40 |
| Books | 2024-01-02 | 60 | 100 |
| Books | 2024-01-03 | 80 | 180 |
| Books | 2024-01-04 | 20 | 200 |
| Books | 2024-01-05 | 100 | 300 |
| Books | 2024-01-06 | 50 | 350 |
| Books | 2024-01-07 | 70 | 420 |
| Books | 2024-01-08 | 30 | 410 |
| Toys | 2024-01-01 | 200 | 200 |
| Toys | 2024-01-02 | 150 | 350 |
| Toys | 2024-01-03 | 100 | 450 |

• Return: category, sale_date, sales, rolling_7day_sum
• Sort by category, sale_date
• Function to use: SUM() OVER (PARTITION BY category ORDER BY sale_date ROWS BETWEEN 6 PRECEDING AND CURRENT ROW)