MySQLstyle

MySQLstyle is a community-driven style guideline for writing SQL code used with MySQL databases. It aims to improve readability and maintainability of queries, schemas, and stored procedures by standardizing naming, formatting, and commenting practices.

There is no official governing body for MySQLstyle; it is adopted by teams and open-source projects to ensure consistency across codebases, tooling, and migrations. The guideline covers identifiers, keyword capitalization, clause structure, join syntax, aliases, quoting, and documentation.

Identifiers and quoting: prefer lower_case with underscores for table and column names, avoid reserved words, and quote identifiers with backticks when needed. Keywords should be written in uppercase and each clause placed on its own line. One of the core principles is to avoid selecting all columns with SELECT *; instead, list required columns.

Join and alias conventions: use explicit JOIN types (INNER JOIN, LEFT JOIN) with the ON clause on a new line for readability, and alias tables with meaningful short names using AS. Indexes and constraints should follow descriptive prefixes such as pk_, fk_, idx_ for easy identification. Comments should be written with -- for inline notes and /* ... */ for blocks.

Example: a simple query formatted according to MySQLstyle: SELECT u.id, u.username, p.total FROM users AS u JOIN payments AS p ON p.user_id = u.id WHERE u.status = 'active' ORDER BY u.created_at DESC; Example 2: schema fragment with explicit syntax: CREATE TABLE `users` ( `id` BIGINT NOT NULL AUTO_INCREMENT, `username` VARCHAR(64) NOT NULL, `email` VARCHAR(128) NOT NULL, `created_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP, PRIMARY KEY (`id`), UNIQUE KEY `idx_users_email` (`email`) );