From 3b9c6393df33abc30fbbfcc009770a18cea394c9 Mon Sep 17 00:00:00 2001
From: mnoskov <bather.plaint5x@icloud.com>
Date: Wed, 18 Mar 2026 13:14:45 +0300
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---
 .../DQL_materialized_view_courses_effectivity.sql | 41 +++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 mnoskov/postgresql/Пет-проект: Онлайн-курсы/2. Создание отчетности (витрин)/DQL_materialized_view_courses_effectivity.sql

diff --git a/mnoskov/postgresql/Пет-проект: Онлайн-курсы/2. Создание отчетности (витрин)/DQL_materialized_view_courses_effectivity.sql b/mnoskov/postgresql/Пет-проект: Онлайн-курсы/2. Создание отчетности (витрин)/DQL_materialized_view_courses_effectivity.sql
new file mode 100644
index 0000000..4e670fc
--- /dev/null
+++ b/mnoskov/postgresql/Пет-проект: Онлайн-курсы/2. Создание отчетности (витрин)/DQL_materialized_view_courses_effectivity.sql	
@@ -0,0 +1,41 @@
+CREATE MATERIALIZED VIEW course_summary AS
+WITH courses_unique_users AS (
+	SELECT
+		e.course_id,
+		count(e.user_id) AS unique_users
+	FROM
+		enrollments e
+	GROUP BY
+		e.course_id
+),
+lessons_results AS (
+	SELECT
+		l.course_id,
+		count(distinct l.id) AS lessons_count,
+		count(lv.lesson_id) AS total_views,
+		min(lv.viewed_at)::date AS first_viewed_at,
+		max(lv.viewed_at)::date AS last_viewed_at
+	FROM
+		lessons l
+	LEFT JOIN
+		lesson_views lv ON l.id = lv.lesson_id
+	GROUP BY
+		l.course_id
+)
+SELECT
+	c.id AS course_id,
+	c.title AS course_title,
+	cuu.unique_users,
+	lr.lessons_count,
+	lr.total_views,
+	round(lr.total_views / cuu.unique_users::numeric, 2) AS avg_views_per_user,
+	lr.first_viewed_at,
+	lr.last_viewed_at
+FROM
+	courses c
+JOIN	
+	courses_unique_users cuu ON c.id = cuu.course_id
+JOIN
+	lessons_results lr ON c.id = lr.course_id
+ORDER BY
+	c.id;
\ No newline at end of file