Migrations live in database/migrations/. The filename starts with a timestamp, which is how Laravel knows the order to run them in.

database/migrations/
├── 0001_01_01_000000_create_users_table.php      ← ships with Laravel
├── 0001_01_01_000001_create_cache_table.php
├── 0001_01_01_000002_create_jobs_table.php
├── 2025_03_10_120000_create_categories_table.php ← yours
└── 2025_03_10_120500_create_posts_table.php      ← runs after categories

1. Generate a migration

   Artisan creates the file for you. If the name follows the pattern create_xxx_table, Laravel even pre-fills the table name.

   
             php artisan make:migration create_categories_table
             php artisan make:migration create_posts_table
           

   ℹ️ Shortcut

   php artisan make:model Post -m creates the model and its migration in one go. You'll meet models in the next lesson.

2. Understand up() and down()

   Every migration has two methods. up() makes the change, and down() undoes it exactly. The Schema facade and a Blueprint object ($table) let you describe columns in PHP instead of SQL.

   
             <?php
   
             use Illuminate\Database\Migrations\Migration;
             use Illuminate\Database\Schema\Blueprint;
             use Illuminate\Support\Facades\Schema;
   
             return new class extends Migration
             {
                 public function up(): void
                 {
                     Schema::create('categories', function (Blueprint $table) {
                         $table->id();                       // BIGINT auto-increment primary key
                         $table->string('name');             // VARCHAR(255)
                         $table->string('slug')->unique();   // no two categories share a slug
                         $table->timestamps();               // created_at + updated_at
                     });
                 }
   
                 public function down(): void
                 {
                     Schema::dropIfExists('categories');
                 }
             };
           

3. Pick the right column types

   Each $table->... call adds one column. Chain modifiers such as ->nullable() or ->default() to fine-tune it.

   Method	Stores	Blog example
   id()	Auto-increment big integer primary key	id
   string('x', 255)	Short text (VARCHAR)	title, slug
   text('x')	Long text	body
   boolean('x')	true / false	is_featured
   unsignedInteger('x')	Whole numbers ≥ 0	views
   timestamp('x')	Date + time	published_at
   json('x')	Structured data	meta
   foreignId('x')	A link to another table's id	user_id

4. Link tables with foreign keys

   A foreign key is a column that points at a row in another table. foreignId('user_id')->constrained() creates the column and tells the database it must match a real users.id. Laravel guesses the table from the column name.

   
             public function up(): void
             {
                 Schema::create('posts', function (Blueprint $table) {
                     $table->id();
                     $table->foreignId('user_id')->constrained()->cascadeOnDelete();
                     $table->foreignId('category_id')->nullable()->constrained()->nullOnDelete();
                     $table->string('title');
                     $table->string('slug')->unique();
                     $table->text('body');
                     $table->unsignedInteger('views')->default(0);
                     $table->timestamp('published_at')->nullable();
                     $table->timestamps();
                 });
             }
   
             public function down(): void
             {
                 Schema::dropIfExists('posts');
             }
           

   cascadeOnDelete() means "delete a user, and their posts go too". nullOnDelete() means "delete a category, and its posts simply become uncategorised". Because posts points at categories, the categories migration must run first, which is why its timestamp is earlier.

5. Run, roll back, start fresh

   These commands are your daily tools. Rollback runs down() on the most recent batch of migrations.

   
             php artisan migrate              # run every migration that hasn't run yet
             php artisan migrate:status       # see which ones have run
             php artisan migrate:rollback     # undo the last batch
             php artisan migrate:fresh        # DROP ALL tables, then migrate from scratch
             php artisan migrate:fresh --seed # same, then fill with seed data
           

   ⚠️ migrate:fresh deletes everything

   It's perfect on your laptop and catastrophic in production. Never run it against a database holding real users' data.

6. Change an existing table with a new migration

   Once a migration has run anywhere other than your own machine, treat it as frozen. To add an excerpt column later, write a new migration that alters the table.

   
             php artisan make:migration add_excerpt_to_posts_table
           

   
             public function up(): void
             {
                 Schema::table('posts', function (Blueprint $table) {
                     $table->string('excerpt', 300)->nullable()->after('title');
                 });
             }
   
             public function down(): void
             {
                 Schema::table('posts', function (Blueprint $table) {
                     $table->dropColumn('excerpt');
                 });
             }
           

   Note Schema::table() (change an existing table) versus Schema::create() (make a new one).

• A migration describes one schema change; up() applies it and down() reverses it.
• Files run in timestamp order, and Laravel logs each one so it never runs twice.
• foreignId('user_id')->constrained() adds the column and the foreign key in one line.
• migrate moves forward, migrate:rollback undoes the last batch, migrate:fresh wipes and rebuilds.
• Never edit a migration that has already run elsewhere; write a new one with Schema::table().