WITH usrs AS
(SELECT *
FROM
(SELECT user_id
FROM tools_shop.orders) AS o
LEFT JOIN
(SELECT user_id
FROM tools_shop.users) AS u ON o.user_id = u.user_id
LEFT JOIN tools_shop.events AS e ON e.user_id = o.user_id),
ord AS
(SELECT CAST(DATE_TRUNC('month', event_time) AS date) AS mnth,
COUNT(event_name) AS cnt
FROM usrs
GROUP BY CAST(DATE_TRUNC('month', event_time) AS date))
SELECT *,
sum(cnt) OVER (
ORDER BY mnth)
FROM ord