Database migration and population using Laravel: Flexibly manage data structure changes

Using Laravel for database migration and filling: Flexible management of data structure changes

Introduction:
During the development process, we often encounter situations where the database structure needs to be modified. Condition. In order to facilitate the management and maintenance of the database, Laravel provides database migration and filling functions. By using migration and population, we can flexibly handle changes to the database structure and ensure database consistency in different development environments. This article will introduce in detail how to use Laravel for database migration and filling, and give code examples.

1. Database migration
Database migration refers to modifying the structure of the database without losing existing data. Laravel provides rich migration functions that can easily create, modify, and delete database objects such as tables, columns, and indexes.

1. Create migration files
   Use the Laravel Artisan command line tool to quickly create migration files. Enter the following command on the command line:

   php artisan make:migration create_users_table --create=users

   This will create a migration file named YYYY_MM_DD_HHMMSS_create_users_table.php in the database/migrations directory.

2. Edit migration file
   Open the migration file just generated, we can add the code to create the table in the up method. For example, we want to create a table named users and add two columns name and email, the code is as follows:

   public function up()
   {
    Schema::create('users', function (Blueprint $table) {
        $table->id();
        $table->string('name');
        $table->string('email')->unique();
        $table->timestamps();
    });
   }

   in After completing the creation of the table, we can also use a series of methods provided by Laravel to modify the table structure, add indexes, etc. For specific methods, please refer to Laravel's official documentation.

3. Perform migration
   Enter the following command on the command line to perform migration:

   php artisan migrate

   Laravel will automatically perform the operations defined in the up method , create the users table.

4. Undo migration
   If you need to undo migration, you can use the following command:

   php artisan migrate:rollback

   Laravel will automatically call the down method of the migration file , cancel the migration operation.

2. Database filling
Database filling is the process of inserting test data or initial data into the database table. Laravel provides powerful filling functions that can easily generate and insert various types of test data.

1. Create a fill file
   Use the Laravel Artisan command line tool to quickly create a fill file. Enter the following command at the command line:

   php artisan make:seeder UsersTableSeeder

   This will create a fill file named UsersTableSeeder.php in the database/seeders directory.

2. Edit the fill file
   Open the fill file just generated and write the code to insert data in the run method. For example, we want to insert 3 pieces of test data into the users table. The code is as follows:

   public function run()
   {
    DB::table('users')->insert([
        ['name' => 'John', 'email' => 'john@example.com'],
        ['name' => 'Jane', 'email' => 'jane@example.com'],
        ['name' => 'Mike', 'email' => 'mike@example.com'],
    ]);
   }

3. Perform the filling
   Enter the following command on the command line to perform the filling :

   php artisan db:seed --class=UsersTableSeeder

   Laravel will automatically execute the run method in the fill file and insert test data into the users table.

4. Undo the filling
   If you need to undo the filling, you can use the following command:

   php artisan db:seed --class=UsersTableSeeder

   Laravel will automatically call the down method of the filling file , delete the populated data.

Summary:
By using Laravel's database migration and filling functions, we can more flexibly manage and maintain changes to the database structure. The combination of migration and filling with code version control tools can ensure the consistency of the database in different development environments and improve team collaboration efficiency. I hope this article will help you master Laravel's database migration and filling functions.

Note: The above code examples are based on Laravel 8.0 version. Different versions of Laravel may have slight differences, please adjust according to the actual situation.

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