exchange-2.0/database/migrations/2020_11_03_122358_create_files_table.php

<?php

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

class CreateFilesTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('files', function (Blueprint $table) {
            $table->id();
            $table->bigInteger('document_id')->unsigned();
            $table->foreign('document_id')->references('id')->on('documents')->onDelete('cascade');
            $table->text('file')->nullable();
            $table->string('file_type')->nullable();
            $table->timestamps();
            $table->softDeletes();
        });
    }

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