SQL Formatter & Validator

Introduction

The SQL Formatter & Validator is a powerful yet user-friendly online tool designed to help developers, database administrators, and SQL beginners format and validate their SQL queries efficiently. This free tool automatically formats SQL commands with proper indentation, capitalization, and spacing according to standard SQL syntax rules, making your queries more readable and maintainable. Additionally, it performs validation checks to identify common syntax errors before you execute them against your database, potentially saving hours of debugging time. Whether you're writing complex database queries, learning SQL, or simply need to clean up messy SQL code, this formatter and validator provides an intuitive interface to improve your SQL workflow instantly.

How to Use This Tool

Using the SQL Formatter & Validator is straightforward:

Enter Your SQL Query: Type or paste your SQL query into the input text area.
Automatic Formatting: The tool automatically formats your SQL in real-time, displaying the result in the output area.
Validation: The tool automatically checks your SQL for syntax errors and displays any issues found.
Copy Formatted SQL: Click the "Copy" button to copy the formatted SQL to your clipboard for use in your applications or database tools.

The interface is designed to be intuitive and responsive, working seamlessly on both desktop and mobile devices.

SQL Formatting Features

Automatic Keyword Capitalization

The formatter automatically capitalizes SQL keywords such as SELECT, FROM, WHERE, JOIN, etc., making them stand out from table and column names. This improves readability and follows standard SQL style conventions.

Proper Indentation

SQL queries are indented according to their logical structure:

Main clauses (SELECT, FROM, WHERE, etc.) start at the left margin
JOIN clauses are indented under FROM
Columns in SELECT statements are aligned
Nested queries receive additional indentation levels
Conditions in WHERE clauses are properly aligned

Line Breaks and Spacing

The formatter inserts line breaks at logical points in your query:

After each main clause (SELECT, FROM, WHERE, etc.)
Between items in a comma-separated list
Before and after subqueries
Between CASE statement components

Proper spacing is also added around operators, parentheses, and between clauses to enhance readability.

SQL Validation Features

The validator checks for common SQL syntax errors and provides clear feedback:

Syntax Error Detection

Unbalanced Parentheses: Detects missing opening or closing parentheses
Unclosed Quotes: Identifies unclosed string literals
Missing Semicolons: Checks if statements end with semicolons
Clause Order: Verifies that SQL clauses appear in the correct order

Common SQL Mistakes

The validator also identifies common logical errors:

JOIN Without ON Condition: Detects JOIN clauses missing their ON conditions
Incomplete WHERE Conditions: Identifies WHERE clauses with incomplete predicates
HAVING Without GROUP BY: Catches HAVING clauses used without a corresponding GROUP BY
Empty Clauses: Detects empty GROUP BY, ORDER BY, or other clauses

Validation Feedback

When errors are detected, they are displayed in a clear, user-friendly format:

Each error is listed with a descriptive message
The type of error is identified
Suggestions for fixing the error may be provided

SQL Formatting Rules

The SQL formatter follows these specific rules to ensure consistent, readable SQL:

Keyword Capitalization

All SQL keywords are capitalized, including:

Statement types: SELECT, INSERT, UPDATE, DELETE, CREATE, ALTER, DROP
Clauses: FROM, WHERE, GROUP BY, HAVING, ORDER BY, LIMIT
Joins: JOIN, INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN
Operators: AND, OR, NOT, IN, BETWEEN, LIKE, IS NULL
Functions: COUNT, SUM, AVG, MAX, MIN, CASE, WHEN, THEN, ELSE, END

Indentation and Line Breaks

Main clauses start at the beginning of a new line
Subqueries are indented with two spaces per nesting level
Comma-separated lists have each item on a new line with appropriate indentation
JOIN clauses are indented under the FROM clause
Conditions in WHERE clauses are aligned for readability

Example: Before and After Formatting

Before Formatting:

1select u.id, u.name, o.order_date from users u join orders o on u.id = o.user_id where o.status = "completed" group by u.id order by u.name;
2

After Formatting:

1SELECT
2  u.id,
3  u.name,
4  o.order_date
5FROM users u
6  JOIN orders o ON u.id = o.user_id
7WHERE
8  o.status = "completed"
9GROUP BY
10  u.id
11ORDER BY
12  u.name;
13

SQL Validation Rules

The validator checks for the following issues:

Structural Validation

Balanced Parentheses: Every opening parenthesis must have a matching closing parenthesis
Quoted Strings: All quotes (single or double) must be properly closed
Statement Termination: SQL statements should end with a semicolon
Clause Order: Clauses must appear in the correct order (FROM after SELECT, WHERE before GROUP BY, etc.)

Semantic Validation

JOIN Conditions: Every JOIN must have an ON or USING clause
WHERE Conditions: WHERE clauses must have complete conditions
GROUP BY Requirements: HAVING clauses require a GROUP BY clause
Column References: Columns referenced in SELECT must be included in GROUP BY when using aggregation

Example: Validation Errors

Invalid SQL with Errors:

1SELECT user_id, COUNT(*) FROM orders
2JOIN users
3WHERE status = 
4GROUP BY
5HAVING count > 10;
6

Validation Errors:

JOIN missing ON condition
Incomplete WHERE condition
Empty GROUP BY clause
HAVING clause referencing undefined column

Use Cases

The SQL Formatter & Validator is valuable in numerous scenarios:

Database Development

Code Review: Format SQL before code reviews to ensure readability
Debugging: Identify syntax errors before executing queries
Documentation: Generate well-formatted SQL for technical documentation
Legacy Code Maintenance: Clean up and standardize old SQL queries

Education and Learning

SQL Training: Help students learn proper SQL formatting conventions
Self-Study: Validate SQL syntax while learning database programming
Teaching: Demonstrate proper SQL structure and formatting in educational settings
Skill Development: Practice writing syntactically correct SQL queries

Team Collaboration

Standardization: Ensure consistent SQL formatting across a development team
Knowledge Sharing: Make complex queries more understandable for team members
Code Quality: Improve overall SQL code quality in shared codebases
Onboarding: Help new team members understand existing SQL queries

Database Administration

Query Optimization: Format complex queries before optimization
Script Management: Maintain readable database maintenance scripts
Migration Scripts: Ensure correctness of database migration SQL
Audit Preparation: Clean up SQL queries for compliance audits

Alternatives

While our SQL Formatter & Validator provides essential functionality, there are alternatives to consider:

Integrated Development Environments (IDEs)

SQL-specific IDEs: Tools like DataGrip, SQL Server Management Studio, or MySQL Workbench offer built-in formatting and validation
Pros: Integrated with database connections, execution, and other features
Cons: Often require installation, may be expensive, and can be resource-intensive

Database-Specific Tools

PostgreSQL: pgFormatter, psql with \e command
MySQL: MySQL Workbench formatter
SQL Server: SSMS formatting options
Pros: Optimized for specific SQL dialects
Cons: Not portable across different database systems

Code Editor Extensions

VS Code Extensions: SQL Beautify, SQL Formatter
Sublime Text Packages: SqlBeautifier
Pros: Integrated with your development environment
Cons: May require configuration, not always available online

Command-Line Tools

sqlformat: Python-based SQL formatting tool
sql-formatter-cli: Node.js-based formatter
Pros: Can be integrated into CI/CD pipelines
Cons: Requires installation and command-line knowledge

History of SQL Formatting and Validation

Evolution of SQL Standards

SQL (Structured Query Language) was developed in the 1970s at IBM, with the first commercial implementation released in 1979. The American National Standards Institute (ANSI) published the first SQL standard in 1986, followed by the International Organization for Standardization (ISO) in 1987.

As SQL evolved through multiple standards (SQL-86, SQL-89, SQL-92, SQL:1999, SQL:2003, SQL:2008, SQL:2011, SQL:2016, and SQL:2019), formatting practices also developed to improve code readability and maintainability.

Development of SQL Formatting Conventions

In the early days of SQL, formatting was inconsistent and largely based on individual preferences. As database systems became more complex and team-based development became common, the need for standardized formatting grew.

Key milestones in SQL formatting history:

1990s: Early SQL style guides began to emerge in organizations
Early 2000s: The rise of object-relational mapping (ORM) tools increased interest in SQL generation and formatting
2010s: Online SQL formatting tools became popular as web applications grew
Present: Automated formatting is now considered a best practice in database development

SQL Validation Evolution

SQL validation has evolved from simple syntax checking to more sophisticated analysis:

Early Database Systems: Provided basic error messages for syntax issues
1990s-2000s: Development of dedicated SQL parsers and validators
2010s: Integration of SQL validation into development workflows and CI/CD pipelines
Present: AI-assisted SQL validation that can suggest improvements and detect potential performance issues

Code Examples

Example 1: Basic SELECT Query

Unformatted:

1select id, first_name, last_name, email from customers where status = 'active' order by last_name, first_name;
2

Formatted:

1SELECT
2  id,
3  first_name,
4  last_name,
5  email
6FROM
7  customers
8WHERE
9  status = 'active'
10ORDER BY
11  last_name,
12  first_name;
13

Example 2: JOIN Query

Unformatted:

1select c.id, c.name, o.order_date, o.total_amount from customers c left join orders o on c.id = o.customer_id where o.order_date >= '2023-01-01' and o.status != 'cancelled' order by o.order_date desc;
2

Formatted:

1SELECT
2  c.id,
3  c.name,
4  o.order_date,
5  o.total_amount
6FROM
7  customers c
8  LEFT JOIN orders o ON c.id = o.customer_id
9WHERE
10  o.order_date >= '2023-01-01'
11  AND o.status != 'cancelled'
12ORDER BY
13  o.order_date DESC;
14

Example 3: Complex Query with Subquery

Unformatted:

1select d.department_name, (select count(*) from employees e where e.department_id = d.id) as employee_count, (select avg(salary) from employees e where e.department_id = d.id) as avg_salary from departments d where d.active = true having employee_count > 0 order by avg_salary desc;
2

Formatted:

1SELECT
2  d.department_name,
3  (
4    SELECT
5      COUNT(*)
6    FROM
7      employees e
8    WHERE
9      e.department_id = d.id
10  ) AS employee_count,
11  (
12    SELECT
13      AVG(salary)
14    FROM
15      employees e
16    WHERE
17      e.department_id = d.id
18  ) AS avg_salary
19FROM
20  departments d
21WHERE
22  d.active = TRUE
23HAVING
24  employee_count > 0
25ORDER BY
26  avg_salary DESC;
27

Programmatic SQL Formatting

Here are examples of how to implement SQL formatting in various programming languages:

1// JavaScript SQL formatting example using sql-formatter library
2const sqlFormatter = require('sql-formatter');
3
4function formatSQL(sql) {
5  return sqlFormatter.format(sql, {
6    language: 'sql',
7    uppercase: true,
8    linesBetweenQueries: 2,
9    indentStyle: 'standard'
10  });
11}
12
13const rawSQL = "select id, name from users where status='active'";
14const formattedSQL = formatSQL(rawSQL);
15console.log(formattedSQL);
16

1# Python SQL formatting example using sqlparse
2import sqlparse
3
4def format_sql(sql):
5    return sqlparse.format(
6        sql,
7        reindent=True,
8        keyword_case='upper',
9        identifier_case='lower',
10        indent_width=2
11    )
12
13raw_sql = "select id, name from users where status='active'"
14formatted_sql = format_sql(raw_sql)
15print(formatted_sql)
16

1// Java SQL formatting example using JSqlParser
2import net.sf.jsqlparser.parser.CCJSqlParserUtil;
3import net.sf.jsqlparser.statement.Statement;
4
5public class SQLFormatter {
6    public static String formatSQL(String sql) throws Exception {
7        Statement statement = CCJSqlParserUtil.parse(sql);
8        return statement.toString()
9            .replaceAll("(?i)SELECT", "\nSELECT")
10            .replaceAll("(?i)FROM", "\nFROM")
11            .replaceAll("(?i)WHERE", "\nWHERE")
12            .replaceAll("(?i)ORDER BY", "\nORDER BY");
13    }
14    
15    public static void main(String[] args) throws Exception {
16        String rawSQL = "select id, name from users where status='active'";
17        String formattedSQL = formatSQL(rawSQL);
18        System.out.println(formattedSQL);
19    }
20}
21

1<?php
2// PHP SQL formatting example
3function formatSQL($sql) {
4    // Replace keywords with uppercase versions
5    $keywords = ['SELECT', 'FROM', 'WHERE', 'JOIN', 'LEFT JOIN', 'RIGHT JOIN', 
6                 'INNER JOIN', 'GROUP BY', 'ORDER BY', 'HAVING', 'LIMIT'];
7    
8    $formattedSQL = $sql;
9    foreach ($keywords as $keyword) {
10        $formattedSQL = preg_replace('/\b' . preg_quote($keyword, '/') . '\b/i', "\n$keyword", $formattedSQL);
11    }
12    
13    // Add indentation
14    $lines = explode("\n", $formattedSQL);
15    $result = '';
16    $indentLevel = 0;
17    
18    foreach ($lines as $line) {
19        $trimmedLine = trim($line);
20        if (!empty($trimmedLine)) {
21            $result .= str_repeat("  ", $indentLevel) . $trimmedLine . "\n";
22        }
23    }
24    
25    return $result;
26}
27
28$rawSQL = "select id, name from users where status='active'";
29$formattedSQL = formatSQL($rawSQL);
30echo $formattedSQL;
31?>
32

Frequently Asked Questions

What is SQL formatting?

SQL formatting is the process of structuring SQL code with proper indentation, line breaks, and capitalization to make it more readable and maintainable. Good SQL formatting follows established conventions like capitalizing keywords, placing clauses on separate lines, and using consistent indentation for nested structures.

Why should I format my SQL queries?

Formatting SQL queries offers several benefits:

Improved readability makes complex queries easier to understand
Easier debugging and maintenance
Better collaboration with team members
Reduced likelihood of syntax errors
Consistent code style across projects
Professional appearance in documentation and presentations

What SQL dialects does this formatter support?

This SQL formatter supports standard SQL syntax that works across most major database systems, including:

MySQL
PostgreSQL
SQL Server (T-SQL)
Oracle
SQLite
MariaDB

While the formatter handles standard SQL well, some dialect-specific features may not be formatted optimally.

Does the validator check for all possible SQL errors?

The validator checks for common syntax errors and structural issues but cannot detect all possible errors, especially those related to:

Database-specific syntax variations
Object existence (tables, columns, etc.)
Data type compatibility
Performance issues
Business logic problems

It's best used as a first line of defense before executing queries against your database.

Can I customize the formatting style?

Currently, the formatter uses a standard style based on widely accepted SQL conventions. Future versions may include customization options for:

Indentation width
Keyword capitalization preferences
Line break placement
Comma positioning (leading vs. trailing)
Parentheses formatting

Is my SQL data secure when using this tool?

Yes, this tool processes all SQL entirely in your browser. Your SQL queries are never sent to any server or stored anywhere. This makes it safe to use with sensitive or proprietary SQL code.

How do I format very large SQL queries?

For very large SQL queries:

Paste the entire query into the input area
The tool will process it automatically, though it may take a moment for complex queries
For extremely large queries (10,000+ characters), you might notice a brief processing delay

Can I use this tool offline?

This web-based tool requires an internet connection to load initially. However, once loaded, it functions entirely in your browser. For completely offline usage, consider:

Browser extensions for SQL formatting
Desktop SQL IDEs with formatting capabilities
Command-line SQL formatting tools

How does the validator handle different SQL versions?

The validator focuses on syntax elements common across SQL versions (SQL-92 and later). It may not recognize some features specific to the latest SQL standards or proprietary extensions. For version-specific validation, consider using tools provided by your database vendor.

Can I integrate this formatter with my IDE or workflow?

While this web tool doesn't offer direct integration, many IDEs have similar formatting capabilities through extensions or plugins. For automated workflows, consider command-line tools like:

sqlformat (Python)
sql-formatter-cli (Node.js)
pgFormatter (PostgreSQL-specific)

References

"SQL Style Guide" by Simon Holywell. https://www.sqlstyle.guide/
"SQL Pretty Printer SQL Formatting Standards." https://www.sqlshack.com/sql-formatting-standards-sql-pretty-printer/
"SQL:2016 Standard." International Organization for Standardization. https://www.iso.org/standard/63555.html
"Formatting SQL Code." PostgreSQL Documentation. https://www.postgresql.org/docs/current/sql-syntax.html
"SQL Server T-SQL Formatting Standards." Microsoft Documentation. https://docs.microsoft.com/en-us/sql/t-sql/

Try our SQL Formatter & Validator today to improve your SQL code quality, readability, and correctness!

SQL Formatter & Validator: Clean, Format & Check SQL Syntax

SQL Formatter & Validator

Documentation

SQL Formatter & Validator

Introduction

How to Use This Tool

SQL Formatting Features

Automatic Keyword Capitalization

Proper Indentation

Line Breaks and Spacing

SQL Validation Features

Syntax Error Detection

Common SQL Mistakes

Validation Feedback

SQL Formatting Rules

Keyword Capitalization

Indentation and Line Breaks

Example: Before and After Formatting

SQL Validation Rules

Structural Validation

Semantic Validation

Example: Validation Errors

Use Cases

Database Development

Education and Learning

Team Collaboration

Database Administration

Alternatives

Integrated Development Environments (IDEs)

Database-Specific Tools

Code Editor Extensions

Command-Line Tools

History of SQL Formatting and Validation

Evolution of SQL Standards

Development of SQL Formatting Conventions

SQL Validation Evolution

Code Examples

Example 1: Basic SELECT Query

Example 2: JOIN Query

Example 3: Complex Query with Subquery

Programmatic SQL Formatting

Frequently Asked Questions

What is SQL formatting?

Why should I format my SQL queries?

What SQL dialects does this formatter support?

Does the validator check for all possible SQL errors?

Can I customize the formatting style?

Is my SQL data secure when using this tool?

How do I format very large SQL queries?

Can I use this tool offline?

How does the validator handle different SQL versions?

Can I integrate this formatter with my IDE or workflow?

References

Feedback

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