Completed Mock-SQL-3

Market Analysis II.sql

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+WITH CTE AS (
+    SELECT u.user_id AS 'seller_id', u.favorite_brand, o.order_date, i.item_brand, RANK() OVER(PARTITION BY u.user_id ORDER BY o.order_date) AS 'rnk' FROM Users u JOIN Orders o ON u.user_id = o.seller_id JOIN Items i ON o.item_id = i.item_id
+),
+ACTE AS (
+    SELECT c.seller_id, c.favorite_brand, c.item_brand AS 'second_item_brand' FROM CTE c WHERE c.rnk = 2
+)
+SELECT u.user_id AS 'seller_id', (
+    CASE
+        WHEN a.seller_id IS NULL THEN 'no'
+        WHEN a.second_item_brand = a.favorite_brand THEN 'yes'
+        ELSE 'no'
+    END 
+) AS '2nd_item_fav_brand' FROM Users u LEFT JOIN ACTE a ON u.user_id = a.seller_id

Tournament Winners.sql

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+WITH CTE AS(
+    SELECT first_player AS 'player', first_score AS 'score' FROM Matches
+    UNION ALL
+    SELECT second_player AS 'player', second_score AS 'score' FROM Matches
+),
+ACTE AS(
+    SELECT p.player_id, p.group_id, SUM(c.score) AS 'total_score' FROM Players p JOIN CTE c ON p.player_id = c.player GROUP BY p.player_id, p.group_id
+),
+ANCTE AS (
+    SELECT group_id, player_id, ROW_NUMBER() OVER (PARTITION BY group_id ORDER BY total_score DESC, player_id ASC) AS 'group_rank' FROM ACTE
+)
+
+SELECT group_id, player_id FROM ANCTE WHERE group_rank = 1