From 6c06823b68d718ddcfe49663bb997513dd3ea3de Mon Sep 17 00:00:00 2001
From: mnoskov <bather.plaint5x@icloud.com>
Date: Wed, 22 Apr 2026 14:06:46 +0300
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---
 .../Пет проект: DWH/Step_3_core_layer.sql     | 112 ++++++++++++++++++
 1 file changed, 112 insertions(+)
 create mode 100644 mnoskov/greenplum/Пет проект: DWH/Step_3_core_layer.sql

diff --git a/mnoskov/greenplum/Пет проект: DWH/Step_3_core_layer.sql b/mnoskov/greenplum/Пет проект: DWH/Step_3_core_layer.sql
new file mode 100644
index 0000000..c21d4fa
--- /dev/null
+++ b/mnoskov/greenplum/Пет проект: DWH/Step_3_core_layer.sql	
@@ -0,0 +1,112 @@
+-- 4
+
+--DROP TABLE IF EXISTS core.dim_user;
+CREATE TABLE core.dim_user (
+	user_id int PRIMARY KEY,
+	name text,
+	age int,
+	email text,
+	registration_date date
+) DISTRIBUTED BY (user_id);
+
+--DROP TABLE IF EXISTS core.dim_course;
+CREATE TABLE core.dim_course (
+	course_id int PRIMARY KEY,
+	title text,
+	category text
+) DISTRIBUTED BY (course_id);
+
+--DROP TABLE IF EXISTS core.dim_lesson;
+CREATE TABLE core.dim_lesson (
+	lesson_id int PRIMARY KEY,
+	title text,
+	duration_min int,
+	course_id int REFERENCES core.dim_course(course_id)
+) DISTRIBUTED BY (lesson_id);
+
+--DROP TABLE IF EXISTS core.dim_date;
+CREATE TABLE core.dim_date (
+	date date PRIMARY KEY,
+	year int,
+	month int,
+	day int,
+	weekday text
+) DISTRIBUTED BY (date);
+
+
+-- 5
+--DROP TABLE IF EXISTS core.fact_lesson_views;
+CREATE TABLE core.fact_lesson_views (
+	user_id int REFERENCES core.dim_user(user_id),
+	lesson_id int REFERENCES core.dim_lesson(lesson_id),
+	course_id int REFERENCES core.dim_course(course_id),
+	viewed_at timestamp
+) DISTRIBUTED BY (user_id);
+
+--DROP TABLE IF EXISTS core.enrollments;
+CREATE TABLE core.enrollments (
+	user_id int REFERENCES core.dim_user(user_id),
+	course_id int REFERENCES core.dim_course(course_id),
+	enrolled_at timestamp
+) DISTRIBUTED BY (user_id);
+
+
+--6
+INSERT INTO core.dim_user (user_id, name, age, email, registration_date)
+SELECT DISTINCT
+	id::int AS user_id,
+	name::text,
+	age::int,
+	email::text,
+	registration_date::date
+FROM raw.users
+WHERE id IS NOT NULL AND email IS NOT NULL;
+
+INSERT INTO core.dim_course (course_id, title, category)
+SELECT DISTINCT
+	id::int AS course_id,
+	title::text,
+	category::text
+FROM
+	raw.courses
+WHERE id IS NOT NULL AND title IS NOT NULL;
+
+INSERT INTO core.dim_lesson (lesson_id, title, duration_min, course_id)
+SELECT DISTINCT
+	id::int AS lesson_id,
+	title::text,
+	duration_min::int,
+	course_id::int
+FROM
+	raw.lessons
+WHERE id IS NOT NULL;
+
+-- загуглил как заполнять:
+INSERT INTO core.dim_date (date, year, month, day, weekday)
+SELECT
+	d::date,
+	EXTRACT(YEAR FROM d)::int,
+	EXTRACT(MONTH FROM d)::int,
+	EXTRACT(DAY FROM d)::int,
+	to_char(d, 'day')
+FROM
+	generate_series('2023-01-01'::date, '2025-12-31'::date, INTERVAL '1 day') AS d;
+
+INSERT INTO core.fact_lesson_views (user_id, lesson_id, course_id, viewed_at)
+SELECT
+	lv.user_id::int,
+	lv.lesson_id::int,
+	l.course_id::int,
+	lv.viewed_at::timestamp
+FROM
+	raw.lesson_views lv
+JOIN
+	raw.lessons l ON lv.lesson_id = l.id
+
+INSERT INTO core.enrollments (user_id, course_id, enrolled_at)
+SELECT
+	user_id::int,
+	course_id::int,
+	enrolled_at::timestamp
+FROM
+	raw.enrollments;
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