# Calculate Monthly Restaurant Sales Growth Write one PostgreSQL SELECT statement or CTE query. Do not create, alter, or modify tables. ## Schema delivery_orders | column | type | |---|---| | delivery_id | integer | | order_place_time | timestamp | | restaurant_id | integer | order_value | column | type | |---|---| | delivery_id | integer | | order_total | numeric | ## Task For restaurant 8, calculate month-over-month percentage sales change for February through December 2021. Assume the restaurant has at least one delivery in every month of 2021. ## Required Output Return sales_month, monthly_sales, previous_month_sales, and growth_pct rounded to two decimal places. Sort by month ascending. ## Constraints - Aggregate monthly sales before using a window function. - Ignore January in the final output but retain it to calculate February growth. - If previous-month sales are zero, return NULL growth rather than dividing by zero. ```hint Lag the monthly total Join orders to values, aggregate by month, and use LAG on those twelve monthly rows. ```