From f7e6b757dfe3b7e664e61ff168dba4b0ddd7bd6e Mon Sep 17 00:00:00 2001
From: mnoskov <bather.plaint5x@icloud.com>
Date: Sat, 21 Mar 2026 20:49:34 +0300
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---
 .../DQL_materialized_view_courses_popularity.sql | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 mnoskov/postgresql/Пет-проект: Онлайн-курсы/2. Создание отчетности (витрин)/DQL_materialized_view_courses_popularity.sql

diff --git a/mnoskov/postgresql/Пет-проект: Онлайн-курсы/2. Создание отчетности (витрин)/DQL_materialized_view_courses_popularity.sql b/mnoskov/postgresql/Пет-проект: Онлайн-курсы/2. Создание отчетности (витрин)/DQL_materialized_view_courses_popularity.sql
new file mode 100644
index 0000000..3377eb5
--- /dev/null
+++ b/mnoskov/postgresql/Пет-проект: Онлайн-курсы/2. Создание отчетности (витрин)/DQL_materialized_view_courses_popularity.sql	
@@ -0,0 +1,39 @@
+CREATE MATERIALIZED VIEW lesson_popularity_ranking as
+WITH lesson_views_results AS (
+	SELECT
+		lv.lesson_id,
+		count(lv.user_id) AS total_views,
+		count(DISTINCT lv.user_id) AS unique_viewers
+	FROM
+		lesson_views lv
+	GROUP BY
+		lv.lesson_id
+),
+enrollments_results AS (
+	SELECT
+		e.course_id,
+		count(e.user_id) AS enrolled_to_course
+	FROM
+		enrollments e
+	GROUP BY
+		e.course_id
+)
+SELECT
+	l.id AS lesson_id,
+	l.title AS lesson_title,
+	c.title AS course_title,
+	lvr.total_views,
+	lvr.unique_viewers,
+	round(lvr.total_views / lvr.unique_viewers::numeric, 2) AS avg_views_per_viewer,
+	dense_rank() OVER (ORDER BY lvr.total_views desc) AS popularity_rank,
+	round((lvr.unique_viewers / er.enrolled_to_course::numeric) * 100, 0) || '%' AS completion_rate
+FROM
+	lessons l
+JOIN
+	courses c ON l.course_id = c.id
+JOIN
+	lesson_views_results lvr ON l.id = lvr.lesson_id
+JOIN
+	enrollments_results er ON c.id = er.course_id
+ORDER BY
+	popularity_rank;
\ No newline at end of file