From 65fc8315c59f4d1ddd41fc013d0ff568abc77edf Mon Sep 17 00:00:00 2001
From: pavel <pmkhlv@gmail.com>
Date: Sat, 14 Feb 2026 13:40:11 +0100
Subject: [PATCH] =?UTF-8?q?homework=20"6)=20=D0=90=D0=B3=D1=80=D0=B5=D0=B3?=
 =?UTF-8?q?=D0=B0=D1=86=D0=B8=D0=B8=20=D0=B8=20=D0=B3=D1=80=D1=83=D0=BF?=
 =?UTF-8?q?=D0=BF=D0=B8=D1=80=D0=BE=D0=B2=D0=BA=D0=B8"=20done?=
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---
 pmikhailov/postgresql/.project                |  11 ++
 .../homework-aggregation-groupby.sql          | 111 ++++++++++++++++++
 2 files changed, 122 insertions(+)
 create mode 100644 pmikhailov/postgresql/.project
 create mode 100644 pmikhailov/postgresql/homework-aggregation-groupby.sql

diff --git a/pmikhailov/postgresql/.project b/pmikhailov/postgresql/.project
new file mode 100644
index 0000000..92f941b
--- /dev/null
+++ b/pmikhailov/postgresql/.project
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>postgresql</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+	</buildSpec>
+	<natures>
+	</natures>
+</projectDescription>
diff --git a/pmikhailov/postgresql/homework-aggregation-groupby.sql b/pmikhailov/postgresql/homework-aggregation-groupby.sql
new file mode 100644
index 0000000..f03b4c4
--- /dev/null
+++ b/pmikhailov/postgresql/homework-aggregation-groupby.sql
@@ -0,0 +1,111 @@
+/* Задание 1 */
+
+SELECT 
+	category,
+	count(*) AS products_count 
+FROM 
+	products p
+GROUP BY category 
+ORDER BY products_count DESC;
+
+
+/* Задание 2
+ * Тут всё решение в задании 
+ *  */
+
+SELECT 
+	order_id,
+	sum(quantity) AS total_quantity,
+	sum(quantity * price_at_purchase) AS order_revenue
+FROM 
+	order_items oi 
+GROUP BY order_id 
+ORDER BY order_revenue DESC;
+
+
+/* Задание 3 */
+
+SELECT 
+	p.category,
+	COALESCE(sum(oi.quantity * oi.price_at_purchase), 0) AS category_revenue
+FROM
+	products p
+LEFT JOIN
+	order_items oi ON p.id = oi.product_id 
+GROUP BY p.category 
+
+
+/* Задание 4 */
+
+SELECT 
+	o.id AS order_id,
+	sum(oi.quantity * oi.price_at_purchase) AS order_revenue 
+FROM
+	orders o 
+LEFT JOIN
+	order_items oi ON o.id = oi.order_id  
+WHERE o.status = 'paid'
+GROUP BY 1
+ORDER BY 2 DESC 
+
+
+/* Задание 5 */
+
+SELECT 
+	p.category,
+	COALESCE(sum(oi.quantity * oi.price_at_purchase), 0) AS category_revenue
+FROM
+	products p
+LEFT JOIN
+	order_items oi ON p.id = oi.product_id 
+GROUP BY 
+	p.category 
+HAVING  
+	sum(oi.quantity * oi.price_at_purchase) > 1;
+
+
+/* Задание 6 */
+
+SELECT 
+	country,
+	count(is_active) AS active_users_count 
+FROM 
+	users u 
+WHERE
+	is_active = TRUE 
+GROUP BY 
+	country
+HAVING 
+	count(is_active) > 2;
+
+
+/* Задание 7 */
+
+SELECT 
+	p.name AS product_name,
+	COALESCE (sum(oi.quantity), 0) AS total_quantity_sold 
+FROM
+	products p 
+LEFT JOIN
+	order_items oi ON p.id = oi.product_id 
+GROUP BY p.name
+ORDER BY 2 DESC 
+LIMIT 3
+
+
+/* Задание 8 
+ * Условие для HAVING в задаче кривое, < 100 ничего нет
+ * */
+
+SELECT 
+	order_id,
+	SUM(quantity * price_at_purchase) AS order_revenue 
+FROM	
+	order_items oi 
+GROUP BY
+	order_id
+HAVING 
+	SUM(quantity * price_at_purchase) < 10000
+ORDER BY 2;
+
+