Understanding Migration in Laravel

What is Migration?

• Migration is like version control for your database.
• It allows teams to define and share the application's database schema.

The Migrate Command

• Command: php artisan migrate
• Purpose: Runs database migrations.
• To understand what it does, use php artisan migrate --help or php artisan migrate -h.

Migration Files

• Located in the database/migrations directory.
• Naming Pattern: timestamp_create_table_name.php
  • Example: 2023_01_01_000000_create_users_table.php

Contents of Migration Files

• Each migration file is responsible for defining one table's schema.
• Example Fields in Users Table Schema:
  • ID (Integer)
  • Name (String)
  • Email (String, Unique)
  • Verified At (Timestamp)
  • Password (String)
  • Remember Token (String)
  • Timestamps (Created At, Updated At)

Running Migrations

• After defining migrations, the command php artisan migrate creates defined tables in the database.
• Example of created tables:
  • Users
  • Password Reset Tokens
  • Jobs
  • Personal Access Tokens

Migrations Table

• Laravel maintains a migrations table that records the migrations that have been run.
• This prevents migrations from being run multiple times.

Updating Migrations

• To update a table, create a new migration using:
  • Command: php artisan make:migration update_users_table
  • Define what to change in the new migration file.
• Rollback: To reverse changes, include down method in migration.

Example of Renaming a Column

• Change column name to username:
  • Use Schema::table('users', function (Blueprint $table) { ... });
  • Don't forget to define the reverse operation in down method.

Checking Migration Status

• Use php artisan migrate:status to check the current status of your migrations.

Final Notes

• Always ensure migrations are well-defined for future updates.
• Keep track of changes to maintain database integrity.