View file database/upgrades/20170922183631_change_user_id_in_flood.php

<?php

use Phinx\Migration\AbstractMigration;
use Phinx\Db\Adapter\MysqlAdapter;

class ChangeUserIdInFlood extends AbstractMigration
{
    /**
     * Migrate Up.
     */
    public function up()
    {
        $table = $this->table('flood');
        $table
            ->changeColumn('user_id', 'integer', ['null' => true])
            ->save();
    }

    /**
     * Migrate Down.
     */
    public function down()
    {
        $table = $this->table('flood');
        $table
            ->changeColumn('user_id', 'integer')
            ->save();
    }
}