Example of generated migration file when we want to modify a table

2018_01_26_113346_adjust_tickets_table.php

<?php

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

class AdjustTicketsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::table('tickets', function (Blueprint $table) {
            $table->timestamp('processed_at')->nullable()->comment("When ticket processed by scheduler");;
            $table->timestamp('completed_at')->nullable()->comment("When ticket completed by scheduler");;
            $table->integer('scheduled_by')->nullable()->comment("Scheduler who schedule the ticket");;
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::table('tickets', function (Blueprint $table) {
            $table->dropColumn(['processed_at', 'completed_at', 'scheduled_by']);
        });
    }
}