SQL Formatter & Minifier

Beautifying & Standardising SQL Queries

Structured Query Language (SQL) queries in enterprise codebases often become convoluted, poorly indented, and difficult to review. Formatting SQL statements according to consistent indentation rules and keyword capitalisation enhances readability, simplifies peer code review, and helps identify missing joins or syntax bugs.

Key SQL Formatting Principles

1. Keyword Capitalisation: Standardise SQL reserved keywords in uppercase (SELECT, FROM, WHERE, JOIN, GROUP BY, ORDER BY).
2. Clause Alignment: Place major clauses on new lines aligned at the left margin.
3. Column Projection: Break multi-column projections across distinct lines indented with 2 or 4 spaces.
4. Predicate Stacking: Align AND and OR boolean predicates beneath the WHERE clause.

Raw Unformatted SQL	Formatted & Readable SQL
select u.id,u.name,o.total from users u inner join orders o on u.id=o.user_id where o.status='completed' and o.total>100 order by o.created_at desc;	<pre>SELECT<br> u.id,<br> u.name,<br> o.total<br>FROM users u<br>INNER JOIN orders o<br> ON u.id = o.user_id<br>WHERE o.status = 'completed'<br> AND o.total > 100<br>ORDER BY o.created_at DESC;</pre>

---

Dialect Support & Syntax Nuances

Different Relational Database Management Systems (RDBMS) support distinct dialects and quoting styles:

• PostgreSQL: Double quotes for identifiers ("tableName"), single quotes for string literals ('value'), :: type casting.
• MySQL / MariaDB: Backticks for identifiers (`tableName`), custom limit syntax (LIMIT 10, 20).
• SQL Server (T-SQL): Square brackets for identifiers ([tableName]), TOP keyword for limiting records.
• Oracle (PL/SQL): Semicolon block delimiters, package references.

---

Formatting SQL Programmatically in Code

JavaScript / Node.js (sql-formatter)

import { format } from 'sql-formatter';

const unformatted = "SELECT id, name, created_at FROM customers WHERE status='active' ORDER BY name ASC";
const formatted = format(unformatted, {
  language: 'postgresql',
  tabWidth: 2,
  keywordCase: 'upper',
  linesBetweenQueries: 2,
});
console.log(formatted);

Python (sqlparse)

import sqlparse

query = "select id, name from products where price > 50 order by name"
formatted = sqlparse.format(
    query,
    reindent=True,
    keyword_case="upper",
    indent_width=2
)
print(formatted)

---

Advanced Query Optimization & Indentation Conventions

• Subquery Formatting: Indent nested subqueries inside parentheses by an extra 2 or 4 spaces to maintain visual isolation between inner and outer scopes.
• Common Table Expressions (CTEs): Format WITH cte_name AS (...) blocks at the top of statements with aligned column lists for modular readability.
• Window Functions: Break complex OVER (PARTITION BY ... ORDER BY ...) clauses across distinct lines for clarity.