Files
homework/mdrozdov/postgresql/dm_user_activity_summary.sql
2026-01-06 16:36:58 +07:00

84 lines
2.7 KiB
SQL

CREATE MATERIALIZED VIEW dm_user_activity_summary as
with enrollment_counts as(
select user_id,
count(course_id) as enrollment_count
from enrollments e
group by user_id
),views as(
select user_id,
count(distinct lesson_id) as viewed_lessons_count,
min(viewed_at) as first_view,
max(viewed_at) as last_view
from lessons_views
group by user_id
), total_lessons as(
select user_id,
count(*) as total_lessons
from enrollments e
join lessons using(course_id)
group by user_id
order by user_id
), engagment_rate as (
select tl.user_id, round(v.viewed_lessons_count*100.0/nullif(total_lessons), 2) as engagment_rate
from total_lessons tl
join views v using(user_id)
)
select u.id, u.name, enrollment_count, viewed_lessons_count, last_view, first_view, engagment_rate
from users u
join enrollment_counts ec on u.id = ec.user_id
join views v on u.id = v.user_id
join engagment_rate er on u.id = er.user_id
order by u.id
/*
--первая попытка сделать витрину, делал избыточно с проверкой каждого подзапроса, поэтому забыл убрать order by, а также больше практиковался в оконных функциях
CREATE MATERIALIZED VIEW user_activity_summary as
with enrollment_counts as(
select distinct user_id,
count(course_id) over (partition by user_id) as enrollment_count
from enrollments e
order by user_id
), viewed_lessons_count as (
select
user_id, count(distinct lesson_id) as viewed_lessons_count
from lessons_views lv
group by user_id
order by user_id
), first_views as(
select
user_id,
viewed_at,
row_number() over (partition by user_id order by viewed_at asc) as rnf
from lessons_views
), last_views as(
select
user_id,
viewed_at,
row_number() over (partition by user_id order by viewed_at desc) as rnl
from lessons_views
), result_views as(
select user_id,
fw.viewed_at as first_view,
lw.viewed_at as last_view
from first_views fw
join last_views lw using(user_id)
where rnf = 1 and rnl = 1
), total_lessons as(
select user_id,
count(*) as total_lessons
from enrollments e
join lessons using(course_id)
group by user_id
order by user_id
), engagment_rate as (
select tl.user_id, round(vlc.viewed_lessons_count*100.0/total_lessons, 2) as engagment_rate
from total_lessons tl
join viewed_lessons_count vlc using(user_id)
)
select u.id, u.name, enrollment_count, viewed_lessons_count, last_view, first_view, engagment_rate
from users u
join enrollment_counts ec on u.id = ec.user_id
join viewed_lessons_count vlc on u.id = vlc.user_id
join result_views rv on u.id = rv.user_id
join engagment_rate er on u.id = er.user_id
order by u.id
*/