A retail company wants to analyze its sales growth month-over-month. Write a SQL query to calculate the sales growth percentage for each month, comparing it to the previous month.
sales (id, sale_date, amount)
| id | sale_date | amount |
|---|---|---|
| 1 | 2024-01-15 | 200 |
| 2 | 2024-01-20 | 300 |
| 3 | 2024-02-10 | 400 |
| 4 | 2024-02-15 | 500 |
| 5 | 2024-03-05 | 600 |
| 6 | 2024-03-20 | 700 |
| 7 | 2024-04-01 | 800 |
| month | growth_percentage |
|---|---|
| 2024-01 | NULL |
| 2024-02 | 50.00 |
| 2024-03 | 25.00 |
| 2024-04 | 14.29 |
