sqldef

sqldef is the easiest idempotent schema management tool for MySQL, PostgreSQL, SQLite3, and SQL Server that uses plain SQL DDLs. Define your desired schema in SQL, and sqldef generates and applies the migrations to update your database.

With sqldef, you maintain a single SQL file with your complete schema. To modify your schema - add columns, change constraints, or create indexes - simply edit this file. sqldef compares desired against current schema and generates the appropriate DDLs, ensuring your database reaches the desired state from any starting point.

Each database gets its own command (mysqldef, psqldef, sqlite3def, mssqldef) that mimics the connection options of the native database client, making it familiar and easy to integrate into existing workflows. The tool comes as a single binary with no dependencies, and provides idempotent operations that are safe to run multiple times.

This is inspired by Ridgepole, which uses Ruby DSL. However, sqldef uses plain SQL, so all you need to remember is SQL.

Supported Databases

• mysqldef - MySQL, MariaDB, and TiDB
• psqldef - PostgreSQL
• sqlite3def - SQLite3
• mssqldef - SQL Server

See CI workflow for tested versions.

Usage

Basic Workflow

This is the basic workflow, which is identical across all databases - only the connection options differ between commands.

Note: Replace $sqldef with the appropriate command for your database:

• mysqldef for MySQL
• psqldef for PostgreSQL
• sqlite3def for SQLite
• mssqldef for SQL Server

1. Export Current Schema

$sqldef [connection-options] --export > schema.sql

Export the existing database schema to review your starting point.

2. Modify the Schema

Edit schema.sql to add, remove, or change columns/tables/indexes:

CREATE TABLE users (
  id BIGINT PRIMARY KEY,
  name VARCHAR(100),
  age INTEGER,  -- Added new column
  created_at TIMESTAMP
);

3. Preview Changes

$sqldef [connection-options] --dry-run < schema.sql

Show the migrations that will be applied without executing them (e.g., ALTER TABLE users ADD COLUMN age INTEGER).

4. Apply Changes

$sqldef [connection-options] --apply < schema.sql

Apply the necessary DDLs to transform current schema to desired state.

Running again shows no changes needed - operations are idempotent.

Offline Mode

sqldef can compare two SQL files without connecting to a database. This is useful for CI/CD pipelines, schema validation, and generating migration scripts.

To use offline mode, specify a .sql file as the database argument:

# Compare current.sql with desired.sql
$sqldef current.sql < desired.sql

See the command documentation for more details on offline mode features.

Examples

See practical examples in the example directory:

# Database mode - apply schema changes to a running database
./example/run.sh psqldef      # PostgreSQL
./example/run.sh mysqldef     # MySQL/MariaDB
./example/run.sh sqlite3def   # SQLite3
./example/run.sh mssqldef     # SQL Server

# Offline mode - compare schema files without database connection
./example/run-offline.sh psqldef      # PostgreSQL
./example/run-offline.sh mysqldef     # MySQL/MariaDB
./example/run-offline.sh sqlite3def   # SQLite3
./example/run-offline.sh mssqldef     # SQL Server

Command Documentation

• mysqldef
• psqldef
• sqlite3def
• mssqldef

Installation

Pre-built binaries

Download the single-binary executable for your favorite database from:

https://github.com/sqldef/sqldef/releases

Docker images

Docker images are available on Docker Hub:

https://hub.docker.com/u/sqldef

Linux

Debian packages are not currently available. Use the pre-built binaries or Docker images instead.

# mysqldef
wget -O - https://github.com/sqldef/sqldef/releases/latest/download/mysqldef_linux_amd64.tar.gz \
  | tar xvz

# psqldef
wget -O - https://github.com/sqldef/sqldef/releases/latest/download/psqldef_linux_amd64.tar.gz \
  | tar xvz

# sqlite3def
wget -O - https://github.com/sqldef/sqldef/releases/latest/download/sqlite3def_linux_amd64.tar.gz \
  | tar xvz

# mssqldef
wget -O - https://github.com/sqldef/sqldef/releases/latest/download/mssqldef_linux_amd64.tar.gz \
  | tar xvz

macOS

Homebrew tap is available.

# mysqldef
brew install sqldef/sqldef/mysqldef

# psqldef
brew install sqldef/sqldef/psqldef

# sqlite3def
brew install sqldef/sqldef/sqlite3def

# mssqldef
brew install sqldef/sqldef/mssqldef

Preview Changes with GitHub Actions

There's a GitHub Action that can preview changes to your database schema:

https://github.com/sqldef/sqldef-preview-action

Development

If you update parser/parser.y, run:

$ make parser

Use the following commands to prepare command line tools and DB servers for running tests.

# Linux
$ sudo apt install mysql-client postgresql-client sqlite3
$ curl https://packages.microsoft.com/keys/microsoft.asc | sudo apt-key add -
$ curl https://packages.microsoft.com/config/ubuntu/22.04/prod.list | sudo tee /etc/apt/sources.list.d/msprod.list
$ sudo apt-get update && sudo apt-get install mssql-tools # then add: export PATH="$PATH:/opt/mssql-tools/bin"

# macOS
$ brew install libpq && brew link --force libpq
$ brew install microsoft/mssql-release/mssql-tools

# Start database
$ docker compose up

# Run all tests
$ make test

# Run *def tests
$ go test ./cmd/*def

# Run a single test
$ go test ./cmd/mysqldef -run=TestApply/CreateTable

Run example scripts

Test all database mode examples:

make test-example

This runs ./example/run.sh for all tools. You need to have the respective databases running:

• ./example/run.sh psqldef - requires PostgreSQL
• ./example/run.sh mysqldef - requires MySQL/MariaDB
• ./example/run.sh sqlite3def - requires SQLite3 (no server needed)
• ./example/run.sh mssqldef - requires SQL Server

Test all offline mode examples (no database required):

make test-example-offline

This runs ./example/run-offline.sh for all tools (psqldef, mysqldef, sqlite3def, mssqldef). These examples demonstrate offline mode (file-to-file comparison) without requiring database connections.

Contributing

Please file a pull request if you have a feature request.

If you're unsure what to do, you may file a "Feature requests" ticket on Discussions and discuss how to implement that with the community.

Releasing

The tagpr and sqldef workflows are used to release sqldef.

1. (optional) A maintainer labels a pull request (PR) with minor or major to manage the next version.
2. When a PR is merged to the default branch, tagpr creates a PR to bump the version and update the CHANGELOG.md ("release PR").
3. A maintainer reviews the release PR and merges it.
4. tagpr creates and pushes a release tag, which triggers the next workflow.
5. sqldef workflows creates a GitHub release, build artifacts, upload them to the GitHub release.

Unless it's a pretty big change that needs a discussion, we encourage sqldef maintainers to merge and release their own Pull Requests without asking/waiting for reviews.

We also expect them to release sqldef as frequently as possible. When there's a behavior change, sqldef should have at least one release on that day.

Maintainers

• @k0kubun
• @knaka (sqlite3def)
• @odz (mssqldef)
• @hokaccha (psqldef)
• @gfx (psqldef)

These are the component they were contributing to when they became a maintainer, but they're allowed to maintain every part of sqldef.

Alumni

• @ytakaya (mssqldef)

License

Unless otherwise noted, the sqldef source files are distributed under the MIT License found in the LICENSE file.

parser is distributed under the Apache Version 2.0 license found in the parser/LICENSE.md file.