코호트 리텐션, SQL 한 쿼리로 끝내기

SQL 코호트 분석

WITH cohort AS (
  SELECT user_id,
         MIN(DATE_TRUNC('week', created_at)) AS cohort_week
  FROM users
  GROUP BY user_id
)
SELECT cohort_week,
       week_num,
       COUNT(DISTINCT user_id) AS retained
FROM cohort_activity
GROUP BY 1, 2;