Merge branch 'main' into OS-233

skonev/postgresql/create_tables.sql

@@ -0,0 +1,45 @@
+BEGIN;
+
+CREATE TABLE SKONEV.users(
+	id INT PRIMARY KEY, 
+	name VARCHAR(100), 
+	age INT, 
+	email VARCHAR(255) UNIQUE, 
+	registration_date DATE NOT NULL
+	);
+
+CREATE TABLE SKONEV.courses(
+	id INT PRIMARY KEY,
+	title TEXT NOT NULL,
+	category VARCHAR(255) CHECK (category IN ('data', 'programming', 'business')),
+	created_at DATE NOT NULL
+	);
+
+CREATE TABLE SKONEV.lessons(
+	id INT PRIMARY KEY, 
+	course_id INT NOT NULL,
+	FOREIGN KEY (course_id) REFERENCES courses(id), 
+	title TEXT NOT NULL, 
+	duration_min INT NOT NULL
+	);
+
+
+CREATE TABLE SKONEV.enrollments(
+	id INT PRIMARY KEY, 
+	user_id INT NOT NULL,
+	FOREIGN KEY (user_id) REFERENCES users(id), 
+	course_id INT NOT NULL,
+	FOREIGN KEY (course_id) REFERENCES courses(id), 
+	enrolled_at DATE NOT NULL
+	);
+
+CREATE TABLE SKONEV.lesson_views(
+	id INT PRIMARY KEY, 
+	user_id INT NOT NULL,
+	FOREIGN KEY (user_id) REFERENCES users(id), 
+	lesson_id INT NOT NULL,
+	FOREIGN KEY (lesson_id) REFERENCES lessons(id), 
+	viewed_at TIMESTAMP NOT NULL
+	);
+
+COMMIT;

skonev/postgresql/dm_course_summary.sql

@@ -0,0 +1,47 @@
+BEGIN;
+
+CREATE MATERIALIZED VIEW course_summary AS 
+WITH courses_users AS (
+SELECT 
+	c.id AS course_id,
+	c.title AS course_name,
+	COUNT(DISTINCT user_id) AS unique_users
+FROM courses c
+LEFT join enrollments e ON c.id = e.course_id 
+GROUP BY c.id, c.title
+), 
+courses_views AS (
+    SELECT 
+        l.course_id, 
+        COUNT(lv.id) AS total_views,
+        MAX(lv.viewed_at) AS last_viewed_at,
+        MIN(lv.viewed_at) AS first_viewed_at
+    FROM lessons l
+    JOIN lesson_views lv ON l.id = lv.lesson_id 
+    GROUP BY l.course_id
+),
+courses_lessons AS (
+	SELECT
+		course_id,
+		COUNT(DISTINCT id) AS lessons_count
+	FROM lessons
+	GROUP BY course_id
+)
+
+SELECT 
+	cu.course_id,
+	cu.course_name,
+	cu.unique_users,
+	cl.lessons_count,
+	cv.total_views,
+	ROUND(cv.total_views::DECIMAL / NULLIF(cu.unique_users, 0), 2) AS avg_views_per_user,
+	cv.first_viewed_at,
+	cv.last_viewed_at
+FROM courses_users cu
+LEFT JOIN courses_views cv USING(course_id)
+LEFT JOIN courses_lessons cl USING(course_id)
+ORDER BY cu.course_id;
+
+COMMIT;
+
+

skonev/postgresql/dm_platform_summary.sql

@@ -0,0 +1,20 @@
+BEGIN;
+
+CREATE MATERIALIZED VIEW platform_summary AS 
+SELECT
+    (SELECT COUNT(*) FROM users) AS total_users,
+    (SELECT COUNT(*) FROM courses) AS total_courses,
+    (SELECT COUNT(*) FROM lessons) AS total_lessons,
+    (SELECT COUNT(DISTINCT user_id) FROM lesson_views) AS users_with_views,
+    ROUND(
+        (SELECT COUNT(*)::DECIMAL FROM lessons) / 
+        NULLIF((SELECT COUNT(DISTINCT course_id) FROM lessons), 0), 
+        2
+    ) AS avg_lessons_per_course,
+    ROUND(
+        (SELECT COUNT(*)::DECIMAL FROM lesson_views) / 
+        NULLIF((SELECT COUNT(DISTINCT lesson_id) FROM lesson_views), 0), 
+        2
+    ) AS avg_views_per_lesson;
+
+COMMIT;

skonev/postgresql/dm_user_activity_summary.sql

@@ -0,0 +1,38 @@
+BEGIN;
+
+CREATE MATERIALIZED VIEW user_activity_summary AS 
+WITH users_views AS (
+SELECT
+	u.id AS user_id,
+	u.name, 
+	COUNT(DISTINCT lv.lesson_id) AS viewed_lessons_count,
+	MAX(lv.viewed_at) AS last_view,
+	MIN(lv.viewed_at) AS first_view
+FROM users AS u
+JOIN lesson_views AS lv on u.id = lv.user_id
+GROUP BY u.id
+
+),
+users_engagement AS (
+SELECT 
+	e.user_id AS user_id,
+	COUNT(DISTINCT l.id) AS lessons_cnt,
+	COUNT(DISTINCT course_id) AS enrollment_count
+FROM enrollments AS e
+JOIN lessons AS l using(course_id)
+GROUP BY e.user_id
+)
+
+SELECT 
+	uv.user_id,
+	uv.name,
+	ue.enrollment_count,
+	uv.viewed_lessons_count,
+	uv.last_view,
+	uv.first_view,
+	ROUND(uv.viewed_lessons_count::DECIMAL / NULLIF(ue.lessons_cnt, 0) * 100, 2)  AS engagement_rate
+FROM users_views AS uv
+LEFT JOIN users_engagement AS ue using (user_id)
+ORDER BY uv.user_id
+
+COMMIT;

skonev/postgresql/insert_data.sql

@@ -0,0 +1,42 @@
+BEGIN;
+
+INSERT INTO SKONEV.users (id, name, age, email, registration_date)
+VALUES
+(1, 'Alice', 25, 'alice@mail.com', '2023-01-10'),
+(2, 'Bob', 30, 'bob@gmail.com', '2023-02-05'),
+(3, 'Charlie', 22, 'charlie@mail.com', '2023-02-20'),
+(4, 'Diana', 28, 'diana@mail.com', '2023-03-01'),
+(5, 'Ethan', 35, 'ethan@gmail.com', '2023-03-10');
+
+INSERT INTO SKONEV.courses (id, title, category, created_at)
+VALUES
+(1, 'SQL для начинающих', 'data', '2023-01-01'),
+(2, 'Python для анализа данных', 'programming', '2023-01-15'),
+(3, 'BI с нуля', 'business', '2023-03-01');
+
+INSERT INTO SKONEV.lessons (id, course_id, title, duration_min)
+VALUES
+(1, 1, 'SELECT и FROM', 10),
+(2, 1, 'JOIN', 15),
+(3, 2, 'Pandas', 20),
+(4, 3, 'Основы BI', 12),
+(5, 3, 'Метрики и дашборды', 18);
+
+INSERT INTO SKONEV.enrollments (id, user_id, course_id, enrolled_at)
+VALUES
+(1, 1, 1, '2023-01-15'),
+(2, 1, 2, '2023-02-01'),
+(3, 2, 1, '2023-01-20'),
+(4, 3, 2, '2023-03-05'),
+(5, 4, 3, '2023-04-01');
+
+INSERT INTO SKONEV.lesson_views (id, user_id, lesson_id, viewed_at)
+VALUES
+(1, 1, 1, '2023-01-16 10:00:00'),
+(2, 1, 2, '2023-01-16 10:15:00'),
+(3, 2, 1, '2023-01-21 09:00:00'),
+(4, 3, 3, '2023-03-06 12:00:00'),
+(5, 4, 4, '2023-04-02 10:00:00'),
+(6, 4, 5, '2023-04-03 10:00:00');
+
+COMMIT;