Final Submission

sql/task1.sql

@@ -1,14 +1,57 @@
 -- Problem 1: Retrieve all products in the Sports category
 -- Write an SQL query to retrieve all products in a specific category.
 
+SELECT * FROM shopify.product_data WHERE category_id = 8;
+
 -- Problem 2: Retrieve the total number of orders for each user
 -- Write an SQL query to retrieve the total number of orders for each user.
 -- The result should include the user ID, username, and the total number of orders.
 
+SELECT 
+    O.user_id, 
+    U.username,
+    COUNT(O.order_id) AS total_orders 
+FROM 
+    shopify.user_data U
+INNER JOIN 
+    shopify.order_data O ON U.user_id = O.user_id
+GROUP BY 
+    U.user_id, U.username;
+
+
 -- Problem 3: Retrieve the average rating for each product
 -- Write an SQL query to retrieve the average rating for each product.
 -- The result should include the product ID, product name, and the average rating.
 
+SELECT * FROM shopify.review_data;
+
+SELECT
+    P.product_id,
+    P.product_name,
+    AVG(R.rating) AS average_rating
+FROM
+    shopify.product_data P
+LEFT JOIN
+    shopify.review_data R ON P.product_id = R.product_id
+GROUP BY
+    P.product_id, P.product_name;
+
+
 -- Problem 4: Retrieve the top 5 users with the highest total amount spent on orders
 -- Write an SQL query to retrieve the top 5 users with the highest total amount spent on orders.
 -- The result should include the user ID, username, and the total amount spent.
+
+SELECT
+    U.user_id,
+    U.username,
+    SUM(O.total_amount) AS total_amount_spent
+FROM
+    shopify.user_data U
+JOIN
+    shopify.order_data O ON U.user_id = O.user_id
+GROUP BY
+    U.user_id, U.username
+ORDER BY
+    total_amount_spent DESC,
+    username
+LIMIT 5;

sql/task2.sql

@@ -3,17 +3,89 @@
 -- The result should include the product ID, product name, and the average rating.
 -- Hint: You may need to use subqueries or common table expressions (CTEs) to solve this problem.
 
+WITH ProductAverageRating AS (
+    SELECT
+        P.product_id,
+        P.product_name,
+        AVG(R.rating) AS average_rating
+    FROM
+        shopify.product_data P
+    LEFT JOIN
+        shopify.review_data R ON P.product_id = R.product_id
+    GROUP BY
+        P.product_id, P.product_name
+)
+SELECT
+    product_id,
+    product_name,
+    average_rating
+FROM (
+    SELECT
+        *,
+        RANK() OVER (ORDER BY average_rating DESC) AS ranking
+    FROM
+        ProductAverageRating
+) AS RankedProducts
+WHERE
+    ranking = 1;
+
 -- Problem 6: Retrieve the users who have made at least one order in each category
 -- Write an SQL query to retrieve the users who have made at least one order in each category.
 -- The result should include the user ID and username.
 -- Hint: You may need to use subqueries or joins to solve this problem.
 
+SELECT
+    U.user_id,
+    U.username
+FROM
+    shopify.user_data U
+JOIN
+    shopify.order_data O ON U.user_id = O.user_id
+JOIN
+    shopify.order_items_data OI ON O.order_id = OI.order_id
+JOIN
+    shopify.product_data P ON OI.product_id = P.product_id
+JOIN
+    shopify.category_data C ON P.category_id = C.category_id
+GROUP BY
+    U.user_id, U.username, C.category_id
+HAVING
+    COUNT(DISTINCT C.category_id) = (SELECT COUNT(*) FROM shopify.category_data);
+
 -- Problem 7: Retrieve the products that have not received any reviews
 -- Write an SQL query to retrieve the products that have not received any reviews.
 -- The result should include the product ID and product name.
 -- Hint: You may need to use subqueries or left joins to solve this problem.
 
+SELECT
+    P.product_id,
+    P.product_name
+FROM
+    shopify.product_data P
+LEFT JOIN
+    shopify.review_data R ON P.product_id = R.product_id
+WHERE
+    R.review_id IS NULL;
+
 -- Problem 8: Retrieve the users who have made consecutive orders on consecutive days
 -- Write an SQL query to retrieve the users who have made consecutive orders on consecutive days.
 -- The result should include the user ID and username.
--- Hint: You may need to use subqueries or window functions to solve this problem.
+-- Hint: You may need to use subqueries or window functions to solve this problem.
+
+WITH UserConsecutiveOrders AS (
+    SELECT
+        user_id,
+        order_date,
+        LAG(order_date) OVER (PARTITION BY user_id ORDER BY order_date) AS prev_order_date
+    FROM
+        shopify.order_data
+)
+SELECT DISTINCT
+    U.user_id,
+    U.username
+FROM
+    shopify.user_data U
+JOIN
+    UserConsecutiveOrders UCO ON U.user_id = UCO.user_id
+WHERE
+    UCO.order_date = UCO.prev_order_date + INTERVAL 1 DAY;

sql/task3.sql

@@ -3,17 +3,105 @@
 -- The result should include the category ID, category name, and the total sales amount.
 -- Hint: You may need to use subqueries, joins, and aggregate functions to solve this problem.
 
+SELECT
+    C.category_id,
+    C.category_name,
+    COALESCE(SUM(O.total_amount), 0) AS total_sales_amount
+FROM
+    shopify.category_data C
+LEFT JOIN
+    shopify.product_data P ON C.category_id = P.category_id
+LEFT JOIN
+    shopify.order_items_data OI ON P.product_id = OI.product_id
+LEFT JOIN
+    shopify.order_data O ON OI.order_id = O.order_id
+GROUP BY
+    C.category_id, C.category_name
+ORDER BY
+    total_sales_amount DESC
+LIMIT 3;
+
 -- Problem 10: Retrieve the users who have placed orders for all products in the Toys & Games
 -- Write an SQL query to retrieve the users who have placed orders for all products in the Toys & Games
 -- The result should include the user ID and username.
 -- Hint: You may need to use subqueries, joins, and aggregate functions to solve this problem.
 
+SELECT
+    U.user_id,
+    U.username
+FROM
+    shopify.user_data U
+JOIN
+    shopify.order_data O ON U.user_id = O.user_id
+JOIN
+    shopify.order_items_data OI ON O.order_id = OI.order_id
+JOIN
+    shopify.product_data P ON OI.product_id = P.product_id
+JOIN
+    shopify.category_data C ON P.category_id = C.category_id
+WHERE
+    C.category_name = 'Toys & Games'
+GROUP BY
+    U.user_id, U.username
+HAVING
+    COUNT(DISTINCT P.product_id) = (SELECT COUNT(*) FROM shopify.product_data WHERE category_id = 
+    (SELECT category_id FROM shopify.category_data WHERE category_name = 'Toys & Games'));
+
 -- Problem 11: Retrieve the products that have the highest price within each category
 -- Write an SQL query to retrieve the products that have the highest price within each category.
 -- The result should include the product ID, product name, category ID, and price.
 -- Hint: You may need to use subqueries, joins, and window functions to solve this problem.
 
+SELECT * FROM shopify.product_data
+
+WITH RankedProducts AS (
+    SELECT
+        product_id,
+        product_name,
+        category_id,
+        price,
+        ROW_NUMBER() OVER (PARTITION BY category_id ORDER BY price DESC) AS rn
+    FROM
+        shopify.product_data
+)
+SELECT
+    product_id,
+    product_name,
+    category_id,
+    price
+FROM
+    RankedProducts
+WHERE
+    rn = 1;
+
 -- Problem 12: Retrieve the users who have placed orders on consecutive days for at least 3 days
 -- Write an SQL query to retrieve the users who have placed orders on consecutive days for at least 3 days.
 -- The result should include the user ID and username.
 -- Hint: You may need to use subqueries, joins, and window functions to solve this problem.
+
+WITH UserConsecutiveOrders AS (
+    SELECT
+        user_id,
+        order_date,
+        LAG(order_date) OVER (PARTITION BY user_id ORDER BY order_date) AS prev_order_date,
+        LEAD(order_date) OVER (PARTITION BY user_id ORDER BY order_date) AS next_order_date
+    FROM
+        shopify.order_data
+)
+SELECT DISTINCT
+    U.user_id,
+    U.username
+FROM
+    shopify.user_data U
+JOIN
+    UserConsecutiveOrders UCO ON U.user_id = UCO.user_id
+WHERE
+    (
+        (UCO.order_date = UCO.prev_order_date + INTERVAL 1 DAY AND UCO.order_date = UCO.next_order_date - INTERVAL 1 DAY) OR
+        (UCO.order_date = UCO.prev_order_date + INTERVAL 1 DAY AND UCO.next_order_date IS NULL) OR
+        (UCO.prev_order_date IS NULL AND UCO.order_date = UCO.next_order_date - INTERVAL 1 DAY)
+    )
+GROUP BY
+    U.user_id, U.username
+HAVING
+    COUNT(DISTINCT UCO.order_date) >= 3;