laracom/database/migrations/2018_03_10_150920_create_attribute_values_table.php

<?php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateAttributeValuesTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('attribute_values', function (Blueprint $table) {
            $table->increments('id');
            $table->string('value');
            $table->unsignedInteger('attribute_id');
            $table->foreign('attribute_id')->references('id')->on('attributes');
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('attribute_values');
    }
}