SELECT
date,
channel,
SUM(spend) as total_cost,
SUM(sessions) as total_sessions
FROM (
SELECT ad_date as date, 'Google Ads' as channel, cost as spend, 0 as sessions FROM project.google_ads.data
UNION ALL
SELECT event_date as date, 'GA4' as channel, 0 as spend, count(session_id) as sessions FROM project.ga4.events
UNION ALL
SELECT campaign_date as date, 'Meta Ads' as channel, spend as spend, 0 as sessions FROM project.meta_ads.data
)
GROUP BY 1, 2