We can easily modify the first-touch attribution query to get last-touch attribution: use MAX(timestamp) instead of MIN(timestamp).

For reference, the first-touch attribution query is shown below.

WITH first_touch AS (
    SELECT user_id,
       MIN(timestamp) AS 'first_touch_at'
    FROM page_visits
    GROUP BY user_id)
SELECT ft.user_id,
   ft.first_touch_at,
   pv.utm_source
FROM first_touch AS 'ft'
JOIN page_visits AS 'pv'
   ON ft.user_id = pv.user_id
   AND ft.first_touch_at = pv.timestamp;

Now that you’ve seen how it works, it’s time to practice!