In Laravel, migrations are a feature that allows you to manage database schema changes over time in a structured and version-controlled way.
Here's how migrations work in Laravel:
Migration Files: Migrations are defined as PHP files within the
database/migrations
directory of a Laravel application. Each migration file represents a database schema change, such as creating a new table, adding a column, modifying a column, etc.Schema Definition: Each migration file contains two primary methods:
up()
anddown()
.The
up()
method defines the actions to be performed when applying the migration (e.g., creating a table).The
down()
method defines the actions to be performed when rolling back the migration (e.g., dropping a table).
Command-line Interface (CLI): Laravel provides a command-line interface (CLI) for managing migrations. You can use Artisan commands like
php artisan migrate
to run all outstanding migrations that have not yet been executed against your database. Conversely,php artisan migrate:rollback
will roll back the last batch of migrations.Version Control: Migrations are a part of Laravel's database version control system. Each migration file has a timestamp in its filename, which Laravel uses to determine the order in which migrations should be executed. This ensures that database changes are applied in a predictable and sequential manner.
Migration Status: Laravel keeps track of which migrations have already been executed in the database. This is managed through a special migrations table (
migrations
by default), which records the migration files that have been applied.
By using migrations, you can make database changes across different development environments (e.g., local, staging, production) in a consistent and repeatable manner. Migrations help keep your database schema in sync with your application's codebase and enable collaborative development by allowing developers to share and apply database changes easily. They also provide a convenient way to roll back changes when necessary, helping to maintain database integrity and consistency.