I’m working on a database with two tables: users and orders. Each order is linked to one user. I need to get a list of all users and their most recent order in a single SQL query. What’s the most efficient way to do this? Here’s my table structure:
- users:
user_id, username
- orders:
order_id, user_id, product_id, order_date
I’m also wondering about:
- Any tips for optimizing indexes for this query?
- Would it be faster to add a ‘latest_order’ column to the users table?
- If
order_id is always in order by date, can I use LIMIT 1 to simplify things?
Thanks for any help!
ooh, interesting question! have u considered using window functions? something like ROW_NUMBER() OVER (PARTITION BY user_id ORDER BY order_date DESC) might work. it could be more efficient for larger datasets. what kinda performance are u seeing with your current approach? curious to hear more about ur use case!
hey there! i’ve dealt with this before. you can use a subquery with MAX(order_date) to get the latest order for each user. something like:
SELECT u., o.
FROM users u
LEFT JOIN orders o ON u.user_id = o.user_id
AND o.order_date = (SELECT MAX(order_date) FROM orders WHERE user_id = u.user_id)
this should do the trick! lemme know if u need more help