SQL 2023 · Aggregation and window functions
Number rows within groups
Number each user's orders from newest to oldest. Filter on this to get the latest per user.
SELECT *, ROW_NUMBER() OVER (PARTITION BY user_id ORDER BY created_at DESC) AS rn FROM orders;
Official SQL 2023 documentation
More aggregation and window functions commands
All aggregation and window functions commands · SQL 2023 cheatsheet