Write SQL for ads metrics and variability

You are given three tables describing ad delivery data for a set of campaigns: ad_impressions(imp_id BIGINT PRIMARY KEY, user_id BIGINT, ad_id BIGINT, campaign_id BIGINT, ts TIMESTAMP) — one row per served ad impression. ad_clicks(click_id BIGINT PRIMARY KEY, imp_id BIGINT, user_id BIGINT, ad_id BIGINT, campaign_id BIGINT, ts TIMESTAMP) — one row per recorded click. The same imp_id can appear in multiple rows when the same impression is clicked more than once. ad_spend(dt…