Laravel遷移是數(shù)據(jù)庫的版本控制工具，通過PHP代碼定義和修改數(shù)據(jù)庫結構，提升協(xié)作效率與環(huán)境一致性。遷移文件包含up()和down()方法，前者用於創(chuàng)建或修改數(shù)據(jù)庫元素，如表和字段，後者則用於回滾變更。例如，創(chuàng)建“users”表時，up()方法定義表結構，而down()方法刪除該表。 Laravel提供Artisan命令簡化遷移流程：使用php artisan make:migration生成遷移文件，結合模型創(chuàng)建時可用php artisan make:model User -mf命令，執(zhí)行遷移用php artisan migrate，回滾用php artisan migrate:rollback，重置則用php artisan migrate:fresh。相比直接操作數(shù)據(jù)庫，遷移確保團隊協(xié)作順暢、避免手動SQL錯誤、支持跨環(huán)境復用並提供便捷的回滾機制，極大減少人為錯誤與重複勞動。

Migrations in Laravel are like version control for your database. They let you define and modify your database structure using PHP code, so you can keep your schema organized, share it with others, and apply changes safely across different environments (like local, staging, production).

This makes it easy to collaborate with other developers and ensures everyone is working with the same database structure — no more guessing what table or column names should be.

What do Laravel migrations look like?

A migration file includes two main methods: up() and down() . The up() method adds or modifies database elements (like tables or columns), while down() rolls those changes back.

For example, if you create a migration to add a "users" table, the up() method would define how to create that table, and down() would drop it.

Here's a basic example of what a migration might look like:

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

public function down()
{
    Schema::dropIfExists('users');
}

You don't have to write these manually from scratch — Laravel can generate them for you.

How to create and run migrations

Laravel gives you simple Artisan commands to manage migrations.

To create a new migration file, you can use:

 php artisan make:migration create_users_table

Or if you're creating a model along with the migration:

 php artisan make:model User -mf

That -mf flag creates a model, factory, and a migration all at once.

Once your migration is ready, you run it with:

 php artisan migrate

This applies all pending migrations. If you want to roll back the last batch of migrations (for example, if something went wrong), you can use:

 php artisan migrate:rollback

And if you really want to start over:

 php artisan migrate:fresh

This drops all tables and re-runs all migrations from scratch.

Why using migrations is better than editing the DB directly

• Collaboration : Everyone on the team can stay in sync without manually updating each other's databases.
• Consistency : You avoid mistakes that come from writing raw SQL by hand.
• Reusability : Migrations can be reused across different environments.
• Rollbacks : You can undo changes easily if something breaks.

Without migrations, you'd have to remember every change you made to the database and manually reapply them somewhere else — which is error-prone and time-consuming.

So yeah, migrations are basically a safe, repeatable way to manage your database structure in Laravel. Once you get used to them, you'll probably never want to go back to writing raw SQL again.

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