WITH k AS (

           SELECT CAST(DATE_TRUNC('month', created_at) AS date),

           SUM(costs) OVER(PARTITION BY CAST(DATE_TRUNC('month', created_at) AS date) ORDER BY costs)

           FROM tools_shop.costs)

           SELECT *

           FROM k

           WHERE DATE_TRUNC BETWEEN '2017-01-01' AND '2018-12-31'