You are given two tables for a food delivery platform. `orders`( - `order_id` BIGINT - `customer_id` BIGINT - `restaurant_id` BIGINT - `order_ts` TIMESTAMP - `order_amount` DECIMAL(10,2) - `status` VARCHAR ) `restaurants`( - `restaurant_id` BIGINT - `restaurant_name` VARCHAR - `city` VARCHAR ) Assume `orders.restaurant_id` references `restaurants.restaurant_id`. Use only rows where `status = 'completed'`. Treat each month as a calendar month in UTC. Write SQL for the following tasks: 1. **Monthly percentage of high-frequency customers** A high-frequency customer is a customer who places more than 30 completed orders in the same month. Return: - `month` - `total_customers` - `high_frequency_customers` - `pct_high_frequency` 2. **Top customer per month, excluding high-frequency users** For each month, consider only customers with at most 30 completed orders in that month. Return the customer with the highest monthly order count. Break ties by the smaller `customer_id`. Return: - `month` - `customer_id` - `order_count` 3. **Month-over-month sales growth for 2021** Compute monthly gross sales as the sum of `order_amount` from completed orders in 2021. Return: - `month` - `monthly_sales` - `previous_month_sales` - `mom_growth_pct` Define month-over-month growth as: `(monthly_sales - previous_month_sales) / previous_month_sales` If the previous month's sales are missing or equal to 0, return `NULL` for growth. 4. **Customer reach of bottom-quartile restaurants** For each month, rank restaurants by that month's completed sales and split them into quartiles within the month, where the lowest-sales quartile is the bottom quartile. Compute how many distinct customers ordered from at least one bottom-quartile restaurant, and what share they represent among all monthly customers. Return: - `month` - `customers_reached` - `total_customers` - `pct_customer_reach`