Laravel database migration is created and run through the Artisan command to manage database structure changes. 1. Use php artisan make:migration to generate migration files, such as creating tables or adding fields; 2. Define structure changes in the up() method and define rollback operations in down(); 3. Build table structure through Schema::create() or Schema::table() and pay attention to field details; 4. Use php artisan migrate to run migration, which supports specified paths, database connections and other parameters; 5. You can use migrate:reset or migrate:fresh to reset the structure; 6. It is recommended not to modify the running migration, fill data with Seeder, and pay attention to database differences.

When you start working on projects with Laravel, database migrations are almost an inescapable link. It helps you manage changes in database structure, just like version control, making it easier to collaborate multi-person and synchronize environments. This article will talk about how to create and run database migrations in Laravel.

Create a Migration file

Laravel provides the Artisan command to generate migration files, for example, if you want to create a new user table:

 php artisan make:migration create_users_table

Or you already have a table and want to add a new field, such as adding a bio field to the users table:

 php artisan make:migration add_bio_to_users_table --table=users

After the command is executed, a time stamped file name will be generated in database/migrations directory, such as 2025_04_05_000000_create_users_table.php . This way Laravel can automatically identify the execution order.

There are two methods in the migration file: up() and down() .

• up() is used to apply this migration (such as creating tables or adding fields)
• down() is a rollback operation (such as deleting tables or deleting fields)

What should you pay attention to when writing Migration?

The core of writing migration is to define table structure using the Schema constructor and Blueprint classes provided by Laravel. To give a simple example, create a user table:

 Schema::create('users', function (Blueprint $table) {
    $table->id();
    $table->string('name');
    $table->string('email')->unique();
    $table->timestamp('email_verified_at')->nullable();
    $table->string('password');
    $table->rememberToken();
    $table->timestamps();
});

Here are a few small details that are easy to ignore:

• If you are not using $table->id() , remember to manually specify the primary key and set the autoincrement
• For nullable fields, don't forget to add ->nullable()
• It is very convenient to use timestamps() in timestamp fields, and the defaults are created_at and updated_at
• When deleting foreign keys, some databases (such as MySQL) need to explicitly delete the index, otherwise an error will be reported.

If you just modify the existing table structure, such as adding fields, you can use Schema::table() ) in up() :

 Schema::table('users', function (Blueprint $table) {
    $table->text('bio')->nullable()->after('email');
});

Note: The after() method is only applicable to supported database drivers (such as MySQL), and other databases may not support field order adjustment.

Several ways to run Migration

The most commonly used one is to run it directly:

 php artisan migrate

This command executes all migration files that have not been run.

If you want to only run migrations in a certain directory, you can add the --path parameter:

 php artisan migrate --path=/database/migrations/2025_04_05_create_users_table.php

Or for a database connection (such as you have configured multiple databases):

 php artisan migrate --database=mysql2

If you want to reset the entire database structure, you can roll back first and then run again:

 php artisan migrate:reset
php artisan migrate

It can also be done in one step:

 php artisan migrate:fresh

This command will clear all tables and then run migrations again. It is suitable for use in the development stage, but do not use it in the production environment!

Some practical suggestions and precautions

• Do not manually change the migration you have run . Once it is online, it cannot be modified casually. A new migration should be created to correct the structure.
• Use better with Seeder . Migration is only responsible for the structure, and Seeder is responsible for filling data. The combination of the two can quickly build a test environment.
• Naming must be standardized . Although Laravel automatically sorts by time, clear file names (such as add_status_to_orders_table ) will make you a lot easier to flip in the future.
• Pay attention to the differences in database engines . Certain syntaxes (such as JSON types, foreign key constraints) may perform differently on different databases, especially when you use SQLite for testing and MySQL for formal environments.

Basically that's it. Migration doesn't seem complicated, but is very critical in teamwork and long-term maintenance. Writing well can make the evolution of the database structure clear and controllable.

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