How to Format SQL for Readable, Reviewable Queries

Before and after

select c.id,c.name,sum(o.total) as revenue from customers c join orders o on o.customer_id=c.id where o.created_at>='2026-01-01' and o.status='paid' group by c.id,c.name having sum(o.total)>1000 order by revenue desc limit 20;

SELECT
    c.id,
    c.name,
    SUM(o.total) AS revenue
FROM customers AS c
JOIN orders   AS o ON o.customer_id = c.id
WHERE o.created_at >= '2026-01-01'
  AND o.status = 'paid'
GROUP BY c.id, c.name
HAVING SUM(o.total) > 1000
ORDER BY revenue DESC
LIMIT 20;

Same query, same plan. The second version lets you scan the joins, spot the filters and see the aggregation boundary without parsing the text in your head.

Rules that carry most of the benefit

• Put each major clause — SELECT, FROM, JOIN, WHERE, GROUP BY, ORDER BY — on its own line
• One column per line in the select list once there are more than two or three
• Uppercase keywords, lowercase identifiers, so structure and data names are visually distinct
• Indent AND/OR conditions under WHERE so boolean grouping is obvious
• Always alias tables and always qualify columns in a multi-table query
• Write the join condition on the same line as the join when it is short

Leading vs trailing commas

SELECT
    c.id
  , c.name
  , c.email
FROM customers AS c;

Both conventions are fine. What matters is that your team picks one and a formatter enforces it, so diffs show real changes rather than punctuation churn.

Long queries: use CTEs

WITH paid_orders AS (
    SELECT customer_id, total
    FROM orders
    WHERE status = 'paid'
      AND created_at >= '2026-01-01'
),
revenue AS (
    SELECT customer_id, SUM(total) AS revenue
    FROM paid_orders
    GROUP BY customer_id
)
SELECT c.name, r.revenue
FROM revenue AS r
JOIN customers AS c ON c.id = r.customer_id
ORDER BY r.revenue DESC;

A nested subquery three levels deep is almost always clearer as named CTEs. Each step gets a name, and you can run any step in isolation while debugging.

Common mistakes