Database Configuration and Migrations

# CHAPTER 8

Database Configuration and Migrations #

1. Introduction #

2. Learning Objectives #

• Configure the .env file to connect to MySQL.

• Generate and read Migration files using Artisan.

• Use PHP to define database schemas (tables and columns).

• Execute migrations to automatically build the database.

3. Beginner-Friendly Explanation #

4. Step 1: Configuration (.env) #

DB_CONNECTION=mysql
DB_HOST=127.0.0.1
DB_PORT=3306
DB_DATABASE=laravel_tutorial_db # Make sure this empty DB exists in phpMyAdmin!
DB_USERNAME=root
DB_PASSWORD=

5. Step 2: Creating a Migration File #

php artisan make:migration create_posts_table

Laravel will create a new file in the database/migrations/ directory. The filename will have a timestamp (e.g., 20240101000000createpoststable.php). The timestamp ensures migrations run in the exact order they were created.

6. Step 3: Writing the Schema #

Let's design the posts table:

<?php
use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;

return new class extends Migration
{
    public function up()
    {
        // Schema::create makes a new table called 'posts'
        Schema::create(&#039;posts', function (Blueprint $table) {
            $table->id(); // Creates auto-incrementing Primary Key
            
            $table->string(&#039;title'); // Creates a VARCHAR column
            $table->text(&#039;body');    // Creates a TEXT column
            $table->boolean(&#039;is_published')->default(false);
            
            $table->timestamps(); // Magically creates 'created_at' and 'updated_at' columns!
        });
    }

    public function down()
    {
        // This drops the table if we "rollback" the migration
        Schema::dropIfExists(&#039;posts');
    }
};

7. Step 4: Running the Migration #

php artisan migrate

Laravel connects to your MySQL database, translates your PHP code into raw SQL, and creates the tables perfectly! If you open phpMyAdmin, you will see your new posts table.

8. Rolling Back (Undoing Mistakes) #

php artisan migrate:rollback

Then, you fix the typo in your migration PHP file, and run php artisan migrate again.

9. Best Practices #

• Never Modify Old Migrations: Once a migration has been pushed to a live production server, you *never* edit that file again. If you need to add a new column later, you create a *new* migration (php artisan make:migration addimagetopoststable) that updates the existing table.

10. Common Mistakes #

• SQLSTATE[HY000] [1049] Unknown database: If you run php artisan migrate and get this error, it means you typed DBDATABASE=myapp in your .env file, but you forgot to actually open phpMyAdmin and click "New" to create the blank myapp database first.

• Challenge: Use Artisan to create a migration for a comments table. Add columns for body (text), userid (integer), and postid (integer). Run the migration.

16. Summary #

17. Next Chapter Recommendation #