пет-проект полностью

2026-05-11 04:21:02 +04:00
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+-- Этап 3. Анализ и запросы - Напиши SQL-запросы к витринам -- Напиши свои вариации для практики--
+-- Топ-5 самых просматриваемых уроков
+
+SELECT 
+    lesson_title,
+    course_title,
+    total_views
+FROM lesson_popularity_summary
+ORDER BY total_views DESC
+LIMIT 5;
+
+-- Неактивные пользователи, записавшиеся на курсы
+
+SELECT 
+    name,
+    email,
+    registered_courses_count
+FROM inactive_users_summary
+WHERE registered_courses_count > 0
+ORDER BY registration_date DESC;
+
+-- Курсы с самым высоким процентом завершения
+
+SELECT 
+    course_title,
+    AVG(completion_rate) AS avg_completion
+FROM course_completion_rate
+GROUP BY course_title
+ORDER BY avg_completion DESC
+LIMIT 5;
+
+-- Мои вариации --
+
+-- Среднее количество учеников на урок по каждому курсу
+
+SELECT 
+    course_title,
+    ROUND(AVG(unique_users), 2) AS avg_users_lesson,
+    SUM(total_views) AS total_course_views
+FROM dsolovianov.lesson_popularity_summary
+GROUP BY course_title
+ORDER BY avg_users_lesson DESC;
+
+-- Возрастное распределение неактивных пользователей
+
+SELECT 
+    CASE 
+        WHEN age < 25 THEN 'до 25'
+        WHEN age BETWEEN 25 AND 30 THEN '25-30'
+        WHEN age BETWEEN 31 AND 35 THEN '31-35'
+        ELSE '35+'
+    END AS age_group,
+    COUNT(*) AS inactive_users_count,
+    AVG(registered_courses_count) AS avg_courses_enrolled
+FROM dsolovianov.inactive_users_summary
+GROUP BY age_group
+ORDER BY age_group;
+
+-- Пользователи, которые начали, но не закончили курс (completion_rate между 0 и 1)
+
+SELECT 
+    user_name,
+    course_title,
+    lessons_viewed,
+    lessons_in_course,
+    ROUND(completion_rate * 100, 0) AS no_completion,
+    (lessons_in_course - lessons_viewed) AS remaining_lessons
+FROM dsolovianov.course_completion_rate
+WHERE completion_rate BETWEEN 0.01 AND 0.99
+ORDER BY completion_rate DESC, user_name;
+
+-- Прогресс каждого пользователя по курсам (с указанием статуса)
+
+SELECT 
+    user_name,
+    course_title,
+    lessons_viewed,
+    lessons_in_course,
+    ROUND(completion_rate * 100, 0) AS progress_percent,
+    CASE 
+        WHEN completion_rate = 1.0 THEN 'Пройден'
+        WHEN completion_rate = 0 THEN 'Не начат'
+        WHEN completion_rate >= 0.5 THEN 'В процессе (>50%)'
+        ELSE 'В процессе (<50%)'
+    END AS status
+FROM dsolovianov.course_completion_rate
+ORDER BY user_name, completion_rate DESC;
+