Database Migrations

Quick Introduction

Database Migrations is a single PHP idea you'll use in almost every backend project.

In this lesson you learn only database migrations — not five topics at once. By the end you can write a small working example and explain it in an interview.

We connect each lesson to our course projects: Login System, Blog CMS, REST API, Inventory, Employee Management, and E-Commerce Backend.

Business Problem

You're building the Inventory Management. After a user signs in, you need database migrations working correctly before storing data or showing a dashboard.

Without understanding Database Migrations, the team ships bugs: wrong totals, broken sessions, or type errors that only appear in production. This lesson fixes that with one clear pattern you can copy into your project today.

Core Concept

• Database Migrations is one focused idea — learn it before mixing with other PHP topics.
• Use it in PHP 8.3+ with declare(strict_types=1); at the top of every file.
• Our course project (Inventory Management) uses database migrations in real handlers.
• Run small scripts with php file.php after each change — don't just read.
• Interviewers ask for a one-minute explanation plus a tiny code sample.

Syntax

Core syntax for Database Migrations. Every keyword below appears in production PHP — Laravel and Symfony use the same primitives under the hood.

declare(strict_types=1);

Keywords: declare · strict_types · namespace

Step-by-Step Example

Run this script locally. Change one value, run again, and watch what changes.

<?php
declare(strict_types=1);

// Laravel-style migration (database/migrations/2024_01_01_create_orders_table.php)
use Illuminate\Database\Capsule\Manager as DB;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Capsule\Manager;

Manager::schema()->create('orders', function (Blueprint $table) {
    $table->id();
    $table->foreignId('customer_id')->constrained()->cascadeOnDelete();
    $table->decimal('total', 10, 2);
    $table->string('status', 32)->default('pending');
    $table->timestamps();
    $table->index(['status', 'created_at']);
});

echo 'Migration applied: orders table created';

Line by line

1. — part of the database migrations example; run the file to see the result.
2. declare(strict_types=1); — turns on strict type checking for this file.
3. use Illuminate\Database\Capsule\Manager as DB; — part of the database migrations example; run the file to see the result.
4. use Illuminate\Database\Schema\Blueprint; — part of the database migrations example; run the file to see the result.
5. use Illuminate\Database\Capsule\Manager; — part of the database migrations example; run the file to see the result.

User #42 (user@example.com) balance $19.99

Real-World Example

In the Inventory Management, database migrations appears in a single request handler — not spread across ten files. Keep the example small, test it with php, then paste the pattern into your project branch.

<?php
declare(strict_types=1);

// TODO: Database Migrations exercise for Inventory Management