From 3e09a2cbc769d5e80a64f750cb482848722337cb Mon Sep 17 00:00:00 2001
From: mnoskov <bather.plaint5x@icloud.com>
Date: Sat, 21 Mar 2026 19:49:00 +0300
Subject: [PATCH] =?UTF-8?q?=D0=B2=D0=B8=D1=82=D1=80=D0=B8=D0=BD=D0=B0=20'?=
 =?UTF-8?q?=D0=9A=D0=BE=D0=B3=D0=BE=D1=80=D1=82=D0=BD=D1=8B=D0=B9=20=D0=B0?=
 =?UTF-8?q?=D0=BD=D0=B0=D0=BB=D0=B8=D0=B7=20=D0=BF=D0=BE=D0=BB=D1=8C=D0=B7?=
 =?UTF-8?q?=D0=BE=D0=B2=D0=B0=D1=82=D0=B5=D0=BB=D0=B5=D0=B9'=20=D0=B4?=
 =?UTF-8?q?=D0=BB=D1=8F=20'=D0=9F=D0=B5=D1=82-=D0=BF=D1=80=D0=BE=D0=B5?=
 =?UTF-8?q?=D0=BA=D1=82:=20=D0=9E=D0=BD=D0=BB=D0=B0=D0=B9=D0=BD-=D0=BA?=
 =?UTF-8?q?=D1=83=D1=80=D1=81=D1=8B'?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../DQL_materialized_view_cohort_analysis_of_users.sql | 40 +++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 mnoskov/postgresql/Пет-проект: Онлайн-курсы/2. Создание отчетности (витрин)/DQL_materialized_view_cohort_analysis_of_users.sql

diff --git a/mnoskov/postgresql/Пет-проект: Онлайн-курсы/2. Создание отчетности (витрин)/DQL_materialized_view_cohort_analysis_of_users.sql b/mnoskov/postgresql/Пет-проект: Онлайн-курсы/2. Создание отчетности (витрин)/DQL_materialized_view_cohort_analysis_of_users.sql
new file mode 100644
index 0000000..19b8668
--- /dev/null
+++ b/mnoskov/postgresql/Пет-проект: Онлайн-курсы/2. Создание отчетности (витрин)/DQL_materialized_view_cohort_analysis_of_users.sql	
@@ -0,0 +1,40 @@
+CREATE MATERIALIZED VIEW user_cohort_analysis AS
+WITH users_and_enrollments_results AS (
+	SELECT
+		date_trunc('month', u.registration_date)::date AS cohort_month,
+		count(DISTINCT u.id) AS users_in_cohort,
+		count(DISTINCT e.user_id) AS enrolled_users,
+		count(DISTINCT e.course_id) courses_in_cohort
+	FROM
+		users u
+	JOIN
+		enrollments e ON u.id = e.user_id
+	GROUP BY
+		cohort_month
+),
+lesson_views_results AS (
+	SELECT
+		date_trunc('month', u.registration_date)::date AS cohort_month,
+		count(DISTINCT lv.user_id) AS active_users,
+		round(avg(lv.viewed_at::date - u.registration_date::date), 0) AS avg_time_to_first_view
+	FROM
+		users u
+	LEFT JOIN
+		lesson_views lv ON u.id = lv.user_id
+	GROUP BY
+		cohort_month	
+)
+SELECT
+	uer.cohort_month,
+	uer.users_in_cohort,
+	uer.enrolled_users,
+	lvr.active_users,
+	round((lvr.active_users / uer.users_in_cohort::numeric) * 100, 2) || '%' AS retention_rate,
+	round(uer.courses_in_cohort / uer.users_in_cohort::numeric, 2) AS avg_courses_per_user,
+	lvr.avg_time_to_first_view
+FROM
+	users_and_enrollments_results uer
+JOIN
+	lesson_views_results lvr ON uer.cohort_month = lvr.cohort_month
+ORDER BY
+	uer.cohort_month;
\ No newline at end of file