SQL Formatter: Clean Up Messy SQL Queries in Seconds

Why SQL Formatting Matters

Unformatted SQL is unreadable:

-- ❌ Impossible to parse visually
SELECT u.id,u.name,u.email,o.id,o.total,o.created_at FROM users u JOIN orders o ON u.id=o.user_id WHERE o.total>100 AND u.created_at>'2026-01-01' ORDER BY o.total DESC LIMIT 20;

-- ✅ Instantly readable
SELECT
  u.id,
  u.name,
  u.email,
  o.id,
  o.total,
  o.created_at
FROM users u
  JOIN orders o ON u.id = o.user_id
WHERE
  o.total > 100
  AND u.created_at > '2026-01-01'
ORDER BY o.total DESC
LIMIT 20;

Standard SQL Formatting Rules

Element	Rule	Example
Keywords	UPPERCASE	SELECT, FROM, WHERE
Table names	as-is	users, orders
Aliases	Short, lowercase	u, o, ua
Comparison	Spaces around =	total > 100
Commas	Leading (no trailing)	name, not name ,
Indentation	2 or 4 spaces	Nested clauses indented

Formatting JOINs Correctly

-- ❌ JOINs on same line as FROM
FROM users u JOIN orders o ON u.id=o.user_id

-- ✅ JOINs on separate lines
FROM users u
  JOIN orders o ON u.id = o.user_id
  LEFT JOIN addresses a ON u.id = a.user_id

-- ✅ Multiple conditions
WHERE
  o.total > 100
  AND o.status = 'completed'
  AND a.country IN ('TW', 'HK', 'CN')

Subqueries

SELECT
  u.name,
  (
    SELECT COUNT(*)
    FROM orders o
    WHERE o.user_id = u.id
  ) AS order_count
FROM users u
WHERE
  EXISTS (
    SELECT 1
    FROM orders o
    WHERE o.user_id = u.id
      AND o.total > 500
  )
ORDER BY order_count DESC;

Common Mistakes

Mistake	Correction
select * from	SELECT * FROM (uppercase keywords)
WHERE id=1	WHERE id = 1 (spaces around =)
name ,email	name, email (comma before value)
SELECT id, name, FROM users	Remove trailing comma before FROM
WHERE status='active AND total>100	WHERE status = 'active' AND total > 100

Dialect Differences

Dialect	Extra Keywords
PostgreSQL	RETURNING, ON CONFLICT, WITH ORDINALITY
MySQL	REGEXP, IGNORE, HIGH_PRIORITY
SQLite	RETURNING (v3.35+), ON CONFLICT
T-SQL (SQL Server)	TOP, WITH (nolock)

Online SQL Formatters

Use a formatter that supports dialect selection — formatting rules differ slightly between databases.

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