Recap - Join

Part of the Fundamentals section of Coddy's SQL journey. Lesson 45 of 72.

Challenge

Medium

Available tables and columns:
orders: id, customer_id
products: id, unit_price, units_in_stock
order_items: id, order_id, product_id, quantity

Find the customer IDs of customers who have ordered products with a unit price less than 10, and list the total quantity of those cheap products each customer has ordered.

Return following columns:

customer_id
total_quantity (the sum of quantities of products with a unit price < 10 for each customer)

Try it yourself

-- List the grouping column and the aggregated value the task asks for
SELECT ____
FROM orders
-- Each join needs a condition matching an id column to the column that points at it
INNER JOIN order_items ON ____
INNER JOIN products ON ____
-- Then keep only the rows that meet the threshold the task describes
WHERE ____
GROUP BY orders.customer_id;

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