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Laravel 5框架学习之数据库迁移(Migrations)

Jun 06, 2016 pm 08:05 PM
laravel

本文给大家介绍的是Laravel5框架中最强大的功能之一数据库迁移(database migrations),本文详细给大家介绍数据库迁移的步骤和方法,非常实用,有需要的小伙伴

database migrations 是laravel最强大的功能之一。数据库迁移可以理解为数据库的版本控制器。

在 database/migrations 目录中包含两个迁移文件,一个建立用户表,一个用于用户密码重置。

在迁移文件中,up 方法用于创建数据表,down方法用于回滚,也就是删除数据表。

执行数据库迁移

复制代码 代码如下:


php artisan migrate
#输出
Migration table created successfully.
Migrated: 2014_10_12_000000_create_users_table
Migrated: 2014_10_12_100000_create_password_resets_table

查看mysql数据库,,可以看到产生了三张表。 migratoins 表是迁移记录表,users 和 pasword_resets。

如果设计有问题,执行数据库回滚

复制代码 代码如下:


php artisan migrate:rollback
#输出
Rolled back: 2014_10_12_100000_create_password_resets_table
Rolled back: 2014_10_12_000000_create_users_table

再次查看mysql数据库,就剩下 migrations 表了, users password_resets 被删除了。

修改迁移文件,再次执行迁移。

新建迁移

复制代码 代码如下:


php artisan make:migration create_article_table --create='articles'
#输出
Created Migration: 2015_03_28_050138_create_article_table

在 database/migrations 下生成了新的文件。

increments('id'); $table->timestamps(); }); } /** * Reverse the migrations. * * @return void */ public function down() { Schema::drop('articles'); } }

自动添加了 id列,自动增长,timestamps() 会自动产生 created_at 和 updated_at 两个时间列。我们添加一些字段:

public function up() { Schema::create('articles', function(Blueprint $table) { $table->increments('id'); $table->string('title'); $table->text('body'); $table->timestamp('published_at'); $table->timestamps(); }); }

执行迁移:

复制代码 代码如下:


php artisan migrate

现在有了新的数据表了。

假设我们需要添加一个新的字段,你可以回滚,然后修改迁移文件,再次执行迁移,或者可以直接新建一个迁移文件

复制代码 代码如下:


php artisan make:migration add_excerpt_to_articels_table

查看新产生的迁移文件

只有空的 up 和 down 方法。我们可以手工添加代码,或者我们让laravel为我们生成基础代码。删除这个文件,重新生成迁移文件,注意添加参数:

复制代码 代码如下:


php artisan make:migration add_excerpt_to_articels_table --table='articles'

现在,up 方法里面有了初始代码。

public function up() { Schema::table('articles', function(Blueprint $table) { // }); }

添加实际的数据修改代码:

public function up() { Schema::table('articles', function(Blueprint $table) { $table->text('excerpt')->nullable(); }); } public function down() { Schema::table('articles', function(Blueprint $table) { $table->dropColumn('excerpt'); }); }

nullable() 表示字段也可以为空。

再次执行迁移并检查数据库。

如果我们为了好玩,执行回滚

复制代码 代码如下:


php artisan migrate:rollback

excerpt 列没有了。

以上所述就是本文的全部内容了,希望能够给大家熟练掌握Laravel5框架有所帮助。

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