A Readable SQL Style, Before and After

SQL works the same however it's laid out, but a consistent style makes review and debugging much faster. This is the layout our formatter uses: keywords in capitals, one clause per line, one column per line.

Before

select o.id, c.name, sum(i.qty*i.price) as total from orders o join customers c on c.id=o.customer_id left join items i on i.order_id=o.id where o.created_at>='2026-01-01' and o.status='paid' group by o.id, c.name having sum(i.qty*i.price)>100 order by total desc limit 20

After

SELECT o.id,
  c.name,
  SUM(i.qty * i.price) AS total
FROM orders o
JOIN customers c
ON c.id = o.customer_id
LEFT JOIN items i
ON i.order_id = o.id
WHERE o.created_at >= '2026-01-01'
  AND o.status = 'paid'
GROUP BY o.id,
  c.name
HAVING SUM(i.qty * i.price) > 100
ORDER BY total DESC
LIMIT 20

Conventions worth agreeing on

• Short, meaningful table aliases (o for orders) and always prefix columns once there's a join.
• Explicit JOIN ... ON, never commas in FROM.
• Leading or trailing commas: pick one for the team and let the formatter enforce it.