mysql - Aggregating data percentage wise based on date related criteria from a table

Question

I have legacy tables which tracks flight and had to extract data. We have three tables named booking, airlines and flighttype. Note this is a dummy samples

booking :

id	customer	request_date	airline	flightType	price	currency
1	1	11-20-2020 10:23	1	1	120	Eur
2	1	11-21-2020 10:24	1	2	110	CHF
3	2	11-01-2020 11:25	2	2	120	Eur
4	1	15-01-2020 10:23	1	1	100	Eur
5	1	11-01-2020 11:23	1	2	60	Eur
6	1	12-01-2020 10:23	1	3	35	Eur

Answer 1

I want to see the total revenue of customers who have made multiple booking within x days or customers who have made multiple booking with different set of currencies with x days

You can answer questions like this using window functions. For the first question, this looks like:

select count(distinct customer)
from (select b.*,
             lag(request_date) over (partition by customer order by request_date) as prev_request_date
      from booking b
     ) b
where request_date <= prev_request_date + interval <n> day;