Window Functions Explained

What You Will Learn

• ROW_NUMBER() helps deduplicate and rank rows within groups.
• SUM() OVER() enables running totals without collapsing result rows.
• Partition strategically to keep results accurate and meaningful.

Sample SQL

SELECT user_id, created_at, total_amount,
       ROW_NUMBER() OVER (PARTITION BY user_id ORDER BY created_at DESC) AS rn
FROM orders;

Next Step

Try rewriting this query in your own schema, then use our tools to format and refine it.