dmedvedev/joins.sql

@@ -79,7 +79,7 @@ SELECT
 	o.id AS order_id,
 	o.status AS status
 FROM users u
-FULL JOIN orders o ON o.user_id = u.id;
+LEFT JOIN orders o ON o.user_id = u.id;
 
 /*
 **✅ После выполнения:**
@@ -97,8 +97,8 @@ FULL JOIN orders o ON o.user_id = u.id;
 SELECT 
 	o.user_id AS user_id,
 	u.name AS user_name
-FROM orders o
-FULL JOIN users u ON o.user_id = u.id
+FROM users u
+LEFT JOIN orders o ON o.user_id = u.id
 WHERE user_id IS NULL;
 
 /* **❓ Ответь на вопросы:** 
@@ -119,9 +119,9 @@ SELECT
 	p.name AS product_name,
 	oi.quantity AS quantity
 FROM order_items oi
-FULL JOIN orders o ON o.id = oi.order_id
-FULL JOIN users u ON o.user_id = u.id
-FULL JOIN products p ON p.id = oi.product_id
+JOIN orders o ON o.id = oi.order_id
+JOIN users u ON o.user_id = u.id
+JOIN products p ON p.id = oi.product_id
 WHERE p.name = 'Kindle';
 
 /*Ответь на вопросы:**
@@ -138,9 +138,9 @@ SELECT
 	p.name AS product_name,
 	oi.order_id AS order_id,
 	oi.quantity AS quantity
-FROM order_items oi
-FULL JOIN orders o ON o.id = oi.order_id
-FULL JOIN products p ON p.id = oi.product_id
+FROM products p
+FULL JOIN order_items oi ON p.id = oi.product_id
+ORDER BY p.name
 
 /*❓ Ответь на вопросы:
 что будет в order_id, если товар ни разу не покупали?
@@ -179,9 +179,9 @@ SELECT
 	oi.quantity AS quantity,
 	oi.price_at_purchase AS price_at_purchase
 FROM order_items oi
-FULL JOIN orders o ON o.id = oi.order_id
-FULL JOIN products p ON p.id = oi.product_id
-FULL JOIN users u ON u.id = o.user_id
+JOIN orders o ON o.id = oi.order_id
+JOIN products p ON p.id = oi.product_id
+JOIN users u ON u.id = o.user_id
 WHERE u.name = 'Alice';
 
 /**❓ Ответь на вопросы:**
@@ -195,11 +195,11 @@ SELECT
 	oi.order_id AS order_id,
 	o.user_id AS user_id,
 	o.status AS status,
-	u.name AS name
-FROM order_items oi
-FULL JOIN orders o ON o.id = oi.order_id
-FULL JOIN products p ON p.id = oi.product_id
-FULL JOIN users u ON u.id = o.user_id;
+	oi.product_id AS product
+FROM orders o
+LEFT JOIN order_items oi ON o.id = oi.order_id
+LEFT JOIN products p ON p.id = oi.product_id
+WHERE oi.product_id IS NULL;
 
 /*
 **❓ Ответь на вопросы:**