SQL Query Formatting Best Practices

Why SQL Formatting Matters

SQL is often written once and read many times — by teammates, future-you, or automated audit tools. Good formatting makes structure visible at a glance.

Core Conventions

1. Uppercase SQL Keywords

-- Bad
select id, name from users where active = true;

-- Good
SELECT id, name
FROM users
WHERE active = TRUE;

2. One Clause Per Line

SELECT
  u.id,
  u.email,
  COUNT(o.id) AS order_count
FROM users u
JOIN orders o ON o.user_id = u.id
WHERE u.active = TRUE
GROUP BY u.id, u.email
HAVING COUNT(o.id) > 3
ORDER BY order_count DESC
LIMIT 50;

3. Use Table Aliases Consistently

SELECT
  u.id,
  u.name,
  p.title AS post_title
FROM users u
JOIN posts p ON p.author_id = u.id;

Avoid single-letter aliases for more than 2 tables — use usr, ord, prd instead.

4. Write JOINs Explicitly

-- Avoid
FROM users u, orders o WHERE u.id = o.user_id

-- Prefer
FROM users u
INNER JOIN orders o ON o.user_id = u.id

5. CTEs Over Nested Subqueries

-- Hard to read
SELECT * FROM (SELECT user_id, COUNT(*) AS cnt FROM orders GROUP BY user_id) t WHERE t.cnt > 5;

-- Easy to read
WITH order_counts AS (
  SELECT user_id, COUNT(*) AS cnt
  FROM orders
  GROUP BY user_id
)
SELECT *
FROM order_counts
WHERE cnt > 5;

6. Format Long WHERE Conditions

WHERE
  status = 'active'
  AND created_at >= '2025-01-01'
  AND (
    role = 'admin'
    OR permissions @> ARRAY['write']
  );

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