dmezentsev
46 lines
1.3 KiB
SQL
46 lines
1.3 KiB
SQL
DROP MATERIALIZED VIEW IF EXISTS dmezentsev.course_summary;
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CREATE MATERIALIZED VIEW dmezentsev.course_summary AS
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WITH count_users AS (
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-- Кол-во уникальных пользователей в курсах
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SELECT
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c.id AS course_id,
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c.title AS course_title,
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COUNT(DISTINCT e.user_id) AS unique_users
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FROM dmezentsev.courses c
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LEFT JOIN dmezentsev.enrollments e ON c.id = e.course_id
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GROUP BY c.id, c.title
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),
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count_lessons AS (
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-- Кол-во уроков в курсах
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SELECT
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course_id,
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COUNT(id) AS lessons_count
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FROM dmezentsev.lessons
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GROUP BY course_id
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),
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views_count AS (
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-- Суммарное число просмотров по каждому курсу
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SELECT
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l.course_id,
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COUNT(lv.id) AS total_views,
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MIN(lv.viewed_at) AS first_viewed_at,
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MAX(lv.viewed_at) AS last_viewed_at
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FROM dmezentsev.lessons l
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LEFT JOIN dmezentsev.lesson_views lv ON l.id = lv.lesson_id
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GROUP BY l.course_id
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)
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SELECT
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cu.course_id,
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cu.course_title,
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cu.unique_users,
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cl.lessons_count,
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vc.total_views,
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ROUND(COALESCE(vc.total_views::numeric /
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cu.unique_users, 0), 2) AS avg_views_per_user,
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vc.first_viewed_at,
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vc.last_viewed_at
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FROM count_users cu
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LEFT JOIN count_lessons cl USING (course_id)
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LEFT JOIN views_count vc USING (course_id)
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ORDER BY cu.course_id; |