SQL Formatter

SQL Formatter is a JavaScript library for pretty-printing SQL queries.

It started as a port of a PHP Library, but has since considerably diverged.

It supports various SQL dialects: GCP BigQuery, IBM DB2, Apache Hive, MariaDB, MySQL, Couchbase N1QL, Oracle PL/SQL, PostgreSQL, Amazon Redshift, SingleStoreDB, Snowflake, Spark, SQL Server Transact-SQL, Trino (and Presto). See language option docs for more details.

It does not support:

• Stored procedures.
• Changing of the delimiter type to something else than ;.

→ Try the demo.

Install

Get the latest version from NPM:

npm install sql-formatter-ast

Also available with yarn:

yarn add sql-formatter-ast

Usage

Usage as library

import { format } from 'sql-formatter-ast';

console.log(format('SELECT * FROM tbl', { language: 'mysql' }));

This will output:

SELECT
  *
FROM
  tbl

You can also pass in configuration options:

format('SELECT * FROM tbl', {
  language: 'spark',
  tabWidth: 2,
  keywordCase: 'upper',
  linesBetweenQueries: 2,
});

Placeholders replacement

In addition to formatting, this library can also perform placeholder replacement in prepared SQL statements:

format('SELECT * FROM tbl WHERE foo = ?', {
  params: ["'bar'"],
});

Results in:

SELECT
  *
FROM
  tbl
WHERE
  foo = 'bar'

For more details see docs of params option.

Usage from command line

The CLI tool will be installed under sql-formatter and may be invoked via npx sql-formatter:

sql-formatter -h

usage: sql-formatter [-h] [-o OUTPUT] \
[-l {bigquery,db2,hive,mariadb,mysql,n1ql,plsql,postgresql,redshift,singlestoredb,snowflake,spark,sql,sqlite,transactsql,trino,tsql}] [-c CONFIG] [--version] [FILE]

SQL Formatter

positional arguments:
  FILE            Input SQL file (defaults to stdin)

optional arguments:
  -h, --help      show this help message and exit
  -o, --output    OUTPUT
                    File to write SQL output (defaults to stdout)
  --fix           Update the file in-place
  -l, --language  {bigquery,db2,hive,mariadb,mysql,n1ql,plsql,postgresql,redshift,singlestoredb,snowflake,spark,sql,sqlite,trino,tsql}
                    SQL dialect (defaults to basic sql)
  -c, --config    CONFIG
                    Path to config json file (will use default configs if unspecified)
  --version       show program's version number and exit

By default, the tool takes queries from stdin and processes them to stdout but one can also name an input file name or use the --output option.

echo 'select * from tbl where id = 3' | sql-formatter

select
  *
from
  tbl
where
  id = 3

The tool also accepts a JSON config file with the --config option that takes this form:

{
  "language": "spark",
  "tabWidth": 2,
  "keywordCase": "upper",
  "linesBetweenQueries": 2
}

All fields are optional and all fields that are not specified will be filled with their default values.

Configuration options

• language the SQL dialect to use (when using format()).
• dialect the SQL dialect to use (when using formatDialect() since version 12).
• tabWidth amount of indentation to use.
• useTabs to use tabs for indentation.
• keywordCase uppercases or lowercases keywords.
• indentStyle defines overall indentation style.
• logicalOperatorNewline newline before or after boolean operator (AND, OR, XOR).
• tabulateAlias aligns column aliases vertically (deprecated!).
• commaPosition where to place the comma in column lists (deprecated!).
• expressionWidth maximum number of characters in parenthesized expressions to be kept on single line.
• linesBetweenQueries how many newlines to insert between queries.
• denseOperators packs operators densely without spaces.
• newlineBeforeSemicolon places semicolon on separate line.
• params collection of values for placeholder replacement.
• paramTypes specifies parameter placeholders types to support.

Usage without NPM

If you don't use a module bundler, clone the repository, run npm install and grab a file from /dist directory to use inside a <script> tag. This makes SQL Formatter available as a global variable window.sqlFormatter.

Usage in editors

• VSCode extension
  • Repo
• Vim extension
• Prettier plugin

Frequently Asked Questions

Parse error: Unexpected ... at line ...

The most common cause is that you haven't specified an SQL dialect. Instead of calling the library simply:

format('select [col] from tbl');
// Throws: Parse error: Unexpected "[col] from" at line 1 column 8

pick the proper dialect, like:

format('select [col] from tbl', { language: 'transactsql' });

Or when using the VSCode extension: Settings -> Prettier-SQL: SQLFlavourOverride.

Module parse failed: Unexpected token

This typically happens when bundling an appication with Webpack. The cause is that Babel (through babel-loader) is not configured to support class properties syntax:

    | export default class ExpressionFormatter {
    >   inline = false;

This syntax is widely supported in all major browsers (except old IE) and support for it is included to the default @babel/preset-env.

Possible fixes:

• Update to newer Babel / Webpack
• Switch to @babel/preset-env
• Include plugin @babel/plugin-proposal-class-properties

The future

The development of this formatter is currently in maintenance mode. Bugs will get fixed if feasible, but new features will likely not be added.

I have started a new SQL formatting tool: prettier-plugin-sql-cst.

• It solves several problems which can't be fixed in SQL Formatter because of fundamental problems in its arhictecture.
• It makes use of the Prettier layout algorithm, doing a better job of splitting long expressions to multiple lines.
• It takes much more opinionated approach to SQL formatting, giving only a very limited set of options to adjust the code style.
• It already has full support for SQLite and BigQuery syntax. It should work for the most common SQL code in various other dialects.

Give it a try if you'd like to take your SQL auto-formatting to the next level.

Contributing

Please see CONTRIBUTING.md

License

MIT