> For the complete documentation index, see [llms.txt](https://quantumphp.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://quantumphp.gitbook.io/docs/advanced-features/migration.md).

# Migration

## Overview

Database migrations provide a way to safely and consistently manage schema changes. Quantum's migration system supports creating, applying, reverting, and tracking migrations via CLI and programmatic APIs.

## Migration Concepts

* Migrations are PHP classes that contain `up()` and `down()` methods which apply and revert schema changes.
* Migrations are stored in migration files located in the `/migrations` directory.
* A migrations table tracks which migrations have been applied to the database.

## Migration Actions

Supported actions include:

* create
* alter
* rename
* drop

Each action corresponds to templates used in generated migration files.

### Example Create Migration

```php
use Quantum\Database\Factories\TableFactory;
use Quantum\Migration\QtMigration;

class CreateTableUsers extends QtMigration
{
    public function up(?TableFactory $tableFactory): void
    {
        $table = $tableFactory->create('users');
        $table->addColumn('id', 'integer')->primary()->autoIncrement();
        $table->addColumn('uuid', 'char', 36);
        $table->addColumn('firstname', 'varchar', 255);
        $table->addColumn('lastname', 'varchar', 255);
        $table->addColumn('role', 'varchar', 255);
        $table->addColumn('email', 'varchar', 255);
        $table->addColumn('password', 'varchar', 255);
        $table->addColumn('activation_token', 'varchar', 255)->nullable();
        $table->addColumn('remember_token', 'varchar', 255)->nullable();
        $table->addColumn('access_token', 'varchar', 255)->nullable();
        $table->addColumn('refresh_token', 'varchar', 255)->nullable();
        $table->addColumn('reset_token', 'varchar', 255)->nullable();
        $table->addColumn('otp', 'integer')->nullable();
        $table->addColumn('otp_token', 'varchar', 255)->nullable();
        $table->addColumn('otp_expires', 'timestamp')->nullable();
    }

    public function down(?TableFactory $tableFactory): void
    {
        $tableFactory->drop('users');
    }
}
```

## Generating a Migration

You can generate a migration file using the CLI:

```bash
php qt migration:generate <action> <table_name>
```

Example:

```bash
php qt migration:generate create users
```

This creates a migration file with an up/down template for the specified action.

## Applying Migrations

Apply pending migrations with:

```bash
php qt migration:migrate
```

To downgrade migrations:

```bash
php qt migration:migrate down --step=1
```

You can increase `--step` to revert more migrations.

## MigrationManager Responsibilities

* Loads migration files and determines which migrations need applying or rolling back.
* Checks for the presence of migration tracking table, and creates it if missing.
* Executes migration classes' `up()` or `down()` methods to apply or revert changes.
* Updates the migrations table with applied and removed migration entries.
* Supports migration ordering and stepping through rollback.

## Best Practices

* Always use migrations for schema changes to keep environments synced.
* Review generated migration templates before applying.
* Use migration rollback during development cautiously.
* Keep migration files under version control.

## What to read next

After migration basics, continue with:

* [Database](/docs/advanced-features/database.md)
* [Models](/docs/core-concepts/models.md)
* [Services](/docs/core-concepts/services.md)
* [CLI Console Commands](/docs/cli/console-commands.md#migrations)


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