Calculating monthly sales growth in SQL
Question
Given the table below, called 'sales', can you write a SQL query to show the monthly sales growth by channel? To calculate the monthly sales growth, you can apply the following logic:
sales growth = (current month's sales - prior month's sales) / prior month's sales
| order_id | channel | date | month | sales_total |
|---|---|---|---|---|
| 1 | online | 2018-09-01 | 09 | 100 |
| 2 | online | 2018-09-03 | 09 | 125 |
| 3 | in_store | 2018-10-11 | 10 | 200 |
| 4 | in_store | 2018-08-21 | 08 | 80 |
| 5 | online | 2018-08-13 | 08 | 200 |