![]() ![]() ![]() Number the rows in the orders table so that the most recent order for each customer gets number 1.Our strategy in this solution is the following: However, you need to use the full timestamp to sort the orders in such cases. This works in our case because we don’t have customers making multiple orders on the same day. Note that in our example, we use the order date without information on the exact order time for simplicity. Specifically, we can use a window function to number the rows of our orders table based on the order date, separately for each customer. If we cannot rely on the order ID to define the most recent order, we can add a column that does the job. So, let’s move to the next solution that gives us more control over the output. This solution gets us the output we need, but it relies on orders being indexed sequentially by when it was created. If you want to learn more about CTEs or WITH clauses, check out this introductory article and this interactive Recursive Queries course that covers all kinds of CTEs. I prefer to use CTEs in cases like these because, in my opinion, they have better structure and readability. We have another subquery to list these orders, and yet another query to join the table with the most recent orders with the table with customer information. In the queries above, we use one SELECT statement, or subquery, to find order IDs that correspond to the most recent order for each customer. ON customers.id = last_orders.customer_idĪlternatively, you can do the same using nested subqueries: Last_orders.order_date, last_orders.order_status ![]() SELECT customers.id, customers.first_name, customers.last_name, This solution can be implemented using common table expressions (CTEs).
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