SQL Formatter

What is SQL Formatting?

SQL formatting (also called beautification or pretty-printing) is the process of adding whitespace, indentation, and line breaks to SQL queries to improve readability. Raw SQL—especially when exported from applications or copied from logs—often appears as a single compressed line: `SELECT name,email FROM users WHERE active=1 AND role='admin'`. While functionally correct, this format is difficult to scan, debug, or modify. A formatted version arranges keywords vertically, indents clauses, and uses consistent capitalization, making the query's logical structure immediately visible.

SQL formatting standards emerged from the need for code review and team collaboration. When multiple developers work on database schemas and queries, consistent formatting prevents merge conflicts and speeds up pull request reviews. Major database management systems (MySQL, PostgreSQL, Oracle, SQL Server) don't enforce specific formatting—they parse queries based on syntax, not appearance—so formatting is purely for human benefit.

How Does SQL Formatting Work?

Our formatter uses the open-source `sql-formatter` library (version 15.4.1) to parse and restructure your SQL. When you paste a query and click "Format SQL," the tool tokenizes your code—breaking it into keywords (SELECT, FROM, WHERE), identifiers (table/column names), operators (=, AND, OR), and literals (strings, numbers). It then applies formatting rules: SQL keywords are converted to UPPERCASE for visibility, each major clause (SELECT, FROM, WHERE, JOIN, GROUP BY) starts on a new line, and nested subqueries receive additional indentation (2 spaces by default).

The formatter recognizes SQL dialects (MySQL, PostgreSQL, etc.) and handles dialect-specific syntax like PostgreSQL's `::` casting operator or MySQL's backtick-quoted identifiers. All processing happens locally in your browser using JavaScript—your SQL never leaves your device, ensuring confidentiality for sensitive production queries.

Benefits of Formatted SQL

• Debugging: Syntax errors become obvious when keywords align vertically. A misplaced parenthesis or missing JOIN condition is easier to spot in formatted code.
• Performance Analysis: Database query planners don't care about formatting, but humans analyzing slow queries need to understand join order, subquery nesting, and filter conditions quickly.
• Code Review: Pull requests containing SQL changes are easier to review when formatted consistently. Reviewers can focus on logic changes rather than deciphering compressed syntax.
• Learning SQL: Beginners learn SQL structure faster when examples use clear formatting. Seeing WHERE clauses consistently indented reinforces the concept of query hierarchy.
• Documentation: Technical documentation that includes SQL examples should use formatted queries. Readers copy-paste these examples into their own projects, so readability matters.

SQL Style Conventions

While there's no single "correct" SQL style, common conventions include:

• Keyword Case: UPPERCASE for keywords (SELECT, WHERE) to distinguish them from user-defined names
• Indentation: 2 or 4 spaces per level (avoid tabs due to inconsistent rendering)
• Clause Alignment: Major clauses (FROM, WHERE, GROUP BY) start at the same indentation level
• Comma Placement: "Leading commas" (starting lines with `,`) vs "trailing commas" (ending lines with `,`) is debated; choose one and stay consistent
• Line Length: Limit lines to 80-120 characters for readability in code review tools

Frequently Asked Questions (FAQs)