Extract list of Sellers with TTM > 100k for the last 3 months in SQL (PostgreSQL) - sql

Question

Quick question:
I want to extract a list of sellers with TTM sales > 100k for the last 3 months. I need a snapshot of the data for the last 3-4 months:
Sellers which have TTM sales > 100k in January
Sellers which have TTM sales > 100k in Febr
Sellers which have TTM sales > 100k in March
I want to create it in a dynamic way on which if I want to extract the data for 6 months, only need to change > Jan to > Oct and store the data in a table
Eg. Jan - 100 sellers, Febr. 200 sellers, March - 75 Sellers
Table used:
Seller list (id, marketplace)
Sales (id, marketplace, sale_day, sale_amount)
Output 1 - TTM:
Output 2 - TTM (only sellers > 100k):
This last output has to be dynamic. I want to get the last 3 months data based on a "RUN_DATE". per eligible seller
TTM = Trailing Twelve Months (sales per seller on the last 12 months)
eg. Sales in Jan (Jan 2020 - Dec 2020)
Sales in Febr (Febr 2020 - Jan 2021)
Thise has to be filterer by 100k.
My actual logic is to take a snapshot of them per month Jan , Febr, March and union.

Answer 1

I suspect you want aggregation:
select id, date_trunc('month', sale_date) as yyyymm,
sum(sale_amount) as total_sales
from sales
group by yyyymm, id;
Then for the last 3 months and filtering, you would do:
select id, date_trunc('month', sale_date) as yyyymm,
sum(sale_amount) as total_sales
from sales s
where s.sale_date >= date_trunc('month', now()) - interval '3' month
group by yyyymm, id
having sum(sale_amount) > 100000;