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homework/dmedvedev/11.4 Pet project Cohort_analysis.sql
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Dmitry Medvedev f443cd4855 fix mistakes
2026-07-22 21:15:19 +05:00

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SQL

CREATE MATERIALIZED
VIEW user_cohort_analysis AS
SELECT
TO_CHAR(pu.cohort_month, 'YYYY-MM') AS MONTH,
COUNT(DISTINCT pu.id) AS users_in_cohort,
COUNT(DISTINCT pe.user_id) AS enrolled_users,
COUNT(DISTINCT plv.user_id) AS active_users,
--ROUND(COUNT(DISTINCT plv.user_id) * 100.0 / COUNT(DISTINCT pu.id), 2) || '%' AS retention_rate,
ROUND(COUNT(DISTINCT pe.user_id) * 100.0 / COUNT(DISTINCT pu.id), 2) || '%' AS retention_rate,
ROUND(AVG((SELECT COUNT(pe.id)
FROM pet_enrollments pe)) / COUNT(DISTINCT pu.id), 2) AS avg_courses_per_user,
(SELECT
ROUND(AVG(table_first_viewed_at.first_viewed_at::date - pu2.registration_date::date), 2)
FROM pet_users pu2
LEFT JOIN (
SELECT
plv2.user_id,
MIN(plv2.viewed_at) AS first_viewed_at
FROM pet_lesson_views plv2
GROUP BY plv2.user_id
) AS table_first_viewed_at
ON pu2.id = table_first_viewed_at.user_id
WHERE DATE_TRUNC('month', pu2.registration_date) = pu.cohort_month
) AS avg_time_to_first_view
FROM (
SELECT
*,
DATE_TRUNC('month', registration_date) AS cohort_month
FROM pet_users
) AS pu
LEFT JOIN pet_enrollments pe ON pu.id = pe.user_id
LEFT JOIN pet_lesson_views plv ON pu.id = plv.user_id
GROUP BY pu.cohort_month
ORDER BY pu.cohort_month;