CPM по рекламным кампаниям за последний месяц, рублей за тысячу показов
SQL, по которому посчитано
WITH last_month AS (
SELECT date_trunc('month', max(date)) AS month_start
FROM ads
)
SELECT
a.source,
a.campaign,
sum(a.impressions) AS impressions,
round(sum(a.cost), 2) AS cost,
round(sum(a.cost) / nullif(sum(a.impressions), 0) * 1000, 2) AS cpm
FROM ads a
WHERE a.date >= (SELECT month_start FROM last_month)
GROUP BY a.source, a.campaign
ORDER BY cpm DESC
LIMIT 30