Php phinx迁移'；向上'；与'；改变'；功能

我使用了phinx迁移，使用了它的“up”和“change”函数，但我没有注意到它们之间有任何区别。下面是我的迁移文件

    <?php

use Phinx\Migration\AbstractMigration;

class MediaManager extends AbstractMigration
{

    public function up()
    {
        if($this->hasTable('uss_dish')){
            $dish = $this->table('uss_dish');
            $dish   -> addColumn('coordinates','text',array('after' => 'district_id','default' => NULL))
                    -> save();
        }
    }

    public function change()
    {
        if($this->hasTable('uss_dish')){
            $dish = $this->table('uss_dish');
            $dish   -> addColumn('coordinates','text',array('after' => 'district_id','default' => NULL))
                    -> save();
        }
    }

}

---

Phinx 0.2.0添加了一个称为可逆迁移的新功能。您可以使用

change

方法实现可逆迁移。如果您已经实现了

change

方法，那么实际上不需要写

down

或

up

方法。当在

change

中向上迁移逻辑时，将执行方法，Phinx将为您找出如何自动向下迁移

在定义表结构等时，可逆迁移非常有用

示例（使用更改方法的可逆迁移）

---

fwiw，文档中说，如果“更改”存在，“向上”和“向下”函数将被忽略。
<?php

use Phinx\Migration\AbstractMigration;

class CreateUserLoginsTable extends AbstractMigration
{
    /**
     * Change Method.
     *
     * Write your reversible migrations using this method.
     *
     * More information on writing migrations is available here:
     * http://docs.phinx.org/en/latest/migrations.html#the-abstractmigration-class
     *
     * The following commands can be used in this method and Phinx will
     * automatically reverse them when rolling back:
     *
     *    createTable
     *    renameTable
     *    addColumn
     *    renameColumn
     *    addIndex
     *    addForeignKey
     *
     * Remember to call "create()" or "update()" and NOT "save()" when working
     * with the Table class.
     */
    public function change()
    {
        // create the table
        $table = $this->table('user_logins');
        $table->addColumn('user_id', 'integer')
              ->addColumn('created', 'datetime')
              ->create();
    }

    /**
     * Migrate Up.
     */
    public function up()
    {

    }

    /**
     * Migrate Down.
     */
    public function down()
    {

    }
}

<?php

use Phinx\Migration\AbstractMigration;

class CreateUserLoginsTable extends AbstractMigration
{


    /**
     * Migrate Up.
     */
    public function up()
    {
       // create the table
        $table = $this->table('user_logins');
        $table->addColumn('user_id', 'integer')
              ->addColumn('created', 'datetime')
              ->create();
    }

    /**
     * Migrate Down.
     */
    public function down()
    {
        $this->dropTable('user_logins');
    }
}