4-4 database\migrations\2019_06_22_141111_create_carts_table.php

<?php

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

class CreateCartsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('carts', function (Blueprint $table) {
            $table->increments('id');

            $table->unsignedBigInteger('user_id');
            $table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');

            $table->unsignedInteger('product_id');
            $table->foreign('product_id')->references('id')->on('products')->onDelete('cascade');

            $table->unsignedInteger('amount');

            $table->timestamps();

        });
    }

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