MySQL Query Formatter — Format MySQL SQL Online Free

MySQL has some quirks in its SQL dialect that affect how you should write and format queries. Understanding them helps you write cleaner MySQL-specific code and avoid portability traps if you ever switch databases.

MySQL-specific formatting considerations

MySQL uses backtick quoting for identifiers (table and column names), unlike PostgreSQL which uses double quotes and SQL Server which uses square brackets. If your identifiers are reserved words or contain spaces, backtick them:

-- MySQL: backtick quoting
SELECT `user`.`id`, `order`.`total`
FROM `user`
JOIN `order` ON `order`.`user_id` = `user`.`id`;

-- Better: avoid reserved words as table names
SELECT u.id, o.total
FROM users u
JOIN orders o ON o.user_id = u.id;

MySQL-specific functions to format consistently

-- Date/time formatting (MySQL-specific)
SELECT
  id,
  DATE_FORMAT(created_at, '%d-%m-%Y') AS date_str,
  DATEDIFF(NOW(), created_at) AS days_old,
  TIMESTAMPDIFF(MONTH, created_at, NOW()) AS months_old
FROM orders
WHERE created_at >= DATE_SUB(NOW(), INTERVAL 90 DAY);

GROUP_CONCAT: MySQL's array aggregation

-- Aggregate related data as comma-separated string
SELECT
  u.id,
  u.name,
  GROUP_CONCAT(
    t.name
    ORDER BY t.name
    SEPARATOR ', '
  ) AS tags
FROM users u
LEFT JOIN user_tags ut ON ut.user_id = u.id
LEFT JOIN tags t ON t.id = ut.tag_id
GROUP BY u.id, u.name;

EXPLAIN for query optimization

-- Always check the query plan for slow queries
EXPLAIN SELECT * FROM orders WHERE user_id = 123;

-- More detailed (MySQL 8+)
EXPLAIN ANALYZE SELECT * FROM orders WHERE user_id = 123;

Look for type: ALLin the output (full table scan). That's a signal you need an index on the filtered column.

Consistent formatting saves debugging time

Copy any MySQL query into our SQL Formatter and format it before pasting into documentation or asking for help in Slack. Formatted SQL gets better answers faster.