SQL Formatter

Why format SQL?

Formatted SQL is dramatically easier to read, review, and debug than unformatted SQL. ORM-generated queries, minified API responses, and legacy code often contain SQL on a single line with inconsistent capitalisation and no indentation. Reformatting these queries reveals their logical structure — the JOINs, WHERE clauses, and subqueries — making it possible to understand what the query does without mentally parsing the syntax.

SQL formatting conventions include: capitalising keywords (SELECT, FROM, WHERE, JOIN, ON, AND); placing each major clause on its own line; indenting the column list under SELECT; and aligning ON conditions with their JOIN. These conventions are not enforced by any SQL engine, but following a consistent style reduces cognitive load during code reviews and audits.

Performance aside, readable SQL is also more secure: unformatted SQL in application code is harder to review for injection vulnerabilities. Proper formatting makes it easier to see whether parameterised queries are used consistently.

Common mistakes

• Dialect differences — SQL has many dialects. MySQL uses backtick quoting (`column`), PostgreSQL uses double quotes ("column"), and SQL Server uses square brackets ([column]). Select the right dialect to avoid breaking formatted queries.
• Comments getting stripped — Some formatters strip SQL comments. Inline comments (-- reason for JOIN) explain complex logic and should be preserved in production code.

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