join tasks done

pmikhailov/postgresql/base_sql.sql

@@ -1,188 +0,0 @@
-CREATE TABLE users (
-	id int PRIMARY KEY, -- NOT NULL
-	name varchar(100) NOT NULL,
-	age int,
-	email varchar(100),
-	country varchar(2),
-	is_active boolean,
-	created_at timestamptz NOT NULL
-);
-	
-CREATE TABLE products (
-	id int PRIMARY KEY, 
-	name varchar(100) NOT NULL,
-	category varchar(50),
-	price decimal(10,2) NOT NULL,
-	in_stock BOOLEAN -- или int, потому что или на складе или не на складе
-); 
-	
-CREATE TABLE orders (
-	id int PRIMARY KEY,
-	user_id int, 
-	order_date timestamptz NOT NULL,
-	status varchar(20)
-);
-
-CREATE TABLE order_items (
-	order_id int,
-	product_id int,
-	quantity int NOT NULL,
-	price_at_purchase decimal(10,2) NOT NULL,
-	PRIMARY KEY (order_id, product_id)
-);
-
-INSERT INTO pmikhailov.users
-(id, "name", age, email, country, is_active, created_at) VALUES
-(1, 'Alice', 25, 'alice@example.com', 'US', TRUE, '2024-01-10 10:00:00'),
-(2, 'Bob', 30, 'bob@example.com', 'UK', TRUE, '2024-02-05 09:30:00'),
-(3, 'Carol', 27, 'carol@example.com', 'US', FALSE, '2024-03-01 15:20:00'),
-(4, 'Diana', 22, 'diana@gmail.com', 'US', TRUE, '2024-01-12 08:15:00'),
-(5, 'Evan', 35, 'evan@example.com', 'UK', TRUE, '2024-01-18 19:40:00'),
-(6, 'Farida', 29, 'farida@example.com', 'KZ', TRUE, '2024-02-20 11:05:00'),
-(7, 'George', 31, 'george+test@example.com', 'US', TRUE, '2024-03-05 16:45:00'),
-(8, 'Helen', 24, NULL, 'UK', FALSE, '2024-03-06 08:20:00'),
-(9, 'Ivan', 26, 'ivan@example.com', 'RU', TRUE, '2024-01-11 14:30:00'),
-(10, 'Julia', 28, 'julia@example.com', 'US', TRUE, '2024-03-07 18:05:00');
-
-
-INSERT INTO pmikhailov.products
-(id, "name", category, price, in_stock) VALUES
-(1, 'iPhone 15', 'Электроника', 80000, TRUE),
-(2, 'Kindle', 'Электроника', 15000, TRUE),
-(3, 'Кроссовки Nike', 'Одежда', 9000, TRUE),
-(4, 'Кроссовки NoName', 'Одежда', 3000, FALSE),
-(5, 'Наушники Pro', 'Электроника', 12000, TRUE),
-(6, 'Фитнес-браслет', 'Гаджеты', 6000, TRUE),
-(7, 'Подарочная карта', 'Сервисы', 1000, TRUE);
-
-INSERT INTO pmikhailov.orders
-(id, user_id, order_date, status) VALUES
-(1, 1, '2025-01-10 12:00:00', 'paid'),
-(2, 3, '2025-01-12 09:30:00', 'cancelled'),
-(3, 1, '2025-01-15 18:20:00', 'paid'),
-(4, 2, '2025-01-20 11:05:00', 'created'),
-(5, 4, '2025-02-01 17:45:00', 'paid'),
-(6, 5, '2025-02-10 10:10:00', 'refunded'),
-(7, 7, '2025-03-01 09:00:00', 'paid'),
-(8, 9, '2025-03-05 19:30:00', 'paid');
-
-INSERT INTO pmikhailov.order_items
-(order_id, product_id, quantity, price_at_purchase) VALUES
-(1, 1, 1, 78000),
-(1, 3, 2, 8500),
-(2, 2, 1, 14000),
-(3, 5, 1, 11000),
-(3, 7, 1, 1000),
-(4, 2, 1, 15000),
-(5, 6, 1, 6000),
-(6, 1, 1, 82000),
-(7, 3, 1, 9000),
-(8, 4, 2, 2800);
-
-SELECT id, name, country, created_at, email 
-FROM users 
-ORDER BY created_at DESC, name ASC;
-
-SELECT id, name, country
-FROM users
-WHERE country = 'US'
-ORDER BY name ASC;
-
-SELECT id, name, country
-FROM users
-WHERE country = 'UK'
-ORDER BY name ASC;
-
-SELECT id, name, email
-FROM users u 
-WHERE email IS NOT NULL 
-ORDER BY name ASC;
-
-SELECT DISTINCT lower(email)
-FROM users u
-WHERE email IS NOT null;
-
-SELECT id, name, created_at 
-FROM users
-WHERE created_at >= '2024-02-05 09:30:00.000 +0100'
-ORDER BY created_at DESC 
-LIMIT 2 OFFSET 1;
-
-
-/* Задача 1 */
-
-SELECT 
-	name, 
-	category, 
-	price,
-	price * 1.3 AS price_with_markup,
-	price * 1.5 AS price_with_vat
-FROM 
-	products p 
-WHERE 
-	in_stock IS TRUE 
-	AND price BETWEEN 100 AND 1300;
-
-
-/* Задача 2 */
-
-SELECT 
-	name,
-	price,
-	price * 0.85 AS price_with_discount 
-FROM 
-	products p 
-WHERE 
-	(price <= 100) OR (price >= 1000);
-
-
-/* Задача 3 */
-
-SELECT 
-	id, 
-	name, 
-	category, 
-	price
-FROM 
-	products p 
-WHERE 
-	category IN ('tablet', 'smartphone', 'mouse')
-	AND price >= 100;
-
-
-/* Задача 4 */
-
-SELECT 
-	name, 
-	category, 
-	price
-FROM	
-	products p
-WHERE name NOT ILIKE '%iPhone%';
-
-
-/* Задача 5 */
-
-SELECT 
-	name, 
-	category, 
-	price
-FROM 
-	products p 
-WHERE 
-	name NOT ILIKE '%pro%'
-ORDER BY 
-	price DESC;
-
-SELECT 
-	name, 
-	category, 
-	price
-FROM 
-	products p 
-WHERE 
-	name NOT ILIKE '%mx%';
-ORDER BY 
-	price DESC;
-	
-

pmikhailov/postgresql/joins.sql

@@ -0,0 +1,158 @@
+/* Задача 1
+ * Джойним в таком порядке т.к. не каждый юзер делал заказ
+ * + судя по порядку колонок мы хотим анализировать заказы
+ * (по сути выглядит так же как INNER)
+ * Но в обратном порядке можем увидеть кто не делал заказ
+ * и добавить их в условную рассылку
+ */
+SELECT 
+	o.id AS order_id, 
+	o.order_date, 
+	status, 
+	u."name" AS user_name, 
+	country
+FROM 
+	orders o
+LEFT JOIN 
+	users u ON o.user_id = u.id 
+	
+
+/* Задача 2 */
+	
+SELECT 
+	order_id, 
+	p."name" AS product_name, 
+	quantity, 
+	price_at_purchase
+FROM 
+	order_items oi
+LEFT JOIN 
+	products p ON oi.product_id = p.id  -- AND oi.order_id = 1 из правой таблицы будут NULL там, где оба условия не выполнены 
+WHERE order_id = 1 -- в задании другой номер - 101, надо исправить в Notion, данные на п.4 уже другие
+
+
+/* Задача 3 */
+
+SELECT 
+	order_id, 
+	u."name" AS user_name,
+	p."name" AS product_name, 
+	quantity, 
+	price_at_purchase
+FROM
+	orders o 
+LEFT JOIN 
+	order_items oi ON o.id =  oi.order_id 
+INNER JOIN 
+	users u ON o.id = u.id
+INNER JOIN
+	products p ON oi.product_id = p.id;
+
+
+/* Задача 4 */
+
+SELECT 
+	u."name" AS user_name,
+	o.id AS order_id,
+	status
+FROM 
+	users u 
+LEFT JOIN
+	orders o ON u.id = o.user_id 
+
+
+/* Задача 5 */
+
+SELECT
+	o.user_id,
+	u."name" AS user_name
+FROM
+	users u 
+LEFT JOIN
+	orders o ON u.id = o.id
+WHERE o.user_id IS NOT NULL
+
+
+/* Задача 6 */
+
+SELECT 
+	o.id AS order_id,
+	u.name AS user_name,
+	p.name AS product_name,
+	quantity
+FROM
+	orders o
+LEFT JOIN
+	order_items oi ON o.id = oi.order_id 
+INNER JOIN 
+	products p ON oi.product_id = p.id 
+INNER JOIN 
+	users u ON o.user_id = u.id
+WHERE p."name" ILIKE '%Mi Band 7%';
+
+
+/* Задача 7 */
+
+SELECT 
+	p.name AS product_name,
+	order_id,
+	quantity
+FROM 
+	products p 
+FULL JOIN 
+	order_items oi ON p.id = oi.product_id
+ORDER BY product_name;
+
+
+/* Задача 8 */
+
+SELECT 
+	o.id,
+	u."name" AS user_name,
+	p."name" AS product_name,
+	quantity,
+	price_at_purchase 
+FROM 
+	orders o 
+LEFT JOIN 
+	order_items oi ON o.id = oi.order_id 
+INNER JOIN 
+	users u ON o.user_id = u.id 
+LEFT JOIN
+	products p ON oi.product_id = p.id 
+WHERE 
+	o.status = 'paid';
+
+
+/* Задача 9 */
+
+SELECT 
+	o.id AS order_id,
+	o.order_date,
+	p."name" AS product_name,
+	quantity,
+	price_at_purchase
+FROM
+	orders o
+LEFT JOIN 
+	order_items oi ON o.id = oi.order_id
+INNER JOIN 
+	products p ON oi.product_id = p.id 
+INNER JOIN 
+	users u ON o.user_id = u.id
+WHERE u."name" ILIKE '%alice%';
+
+
+/* Задача 10 
+* Задача противоречит изначальным органичениям NOT NULL
+*/
+
+SELECT 
+	o.id AS order_id,
+	user_id,
+	status
+FROM
+	orders o 
+FULL JOIN
+	order_items oi ON oi.order_id = o.id 
+WHERE product_id IS NULL AND o.status = 'created';