title: How to change database column 'null' to 'nullable' using laravel migration in mysql?
body: <p>This is my vehicles table. I want to change my database structure by using a migration</p>
  
  <pre><code>
  use Illuminate\Support\Facades\Schema;
  use Illuminate\Database\Schema\Blueprint;
  use Illuminate\Database\Migrations\Migration;
  
  class CreateVehiclesTable extends Migration
  {
      /**
       * Run the migrations.
       *
       * @return void
       */
      public function up()
      {
          Schema::create('vehicles', function (Blueprint $table) {
              $table-&gt;increments('id');
              $table-&gt;string('image')-&gt;nullable();
              $table-&gt;string('reg_no')-&gt;unique();
              $table-&gt;string('fuel_type');
              $table-&gt;string('capacity');
              $table-&gt;double('rate');
              $table-&gt;boolean('req_carrier');
              $table-&gt;date('service_date');
              $table-&gt;integer('service_freq_km');
              $table-&gt;integer('service_freq_months');
              $table-&gt;date('insurance_date');
              $table-&gt;integer('insurance_freq_months');
              $table-&gt;date('eco_date');
              $table-&gt;integer('eco_freq_months');
              $table-&gt;date('licence_date');
              $table-&gt;integer('licence_freq_months');
              $table-&gt;integer('current_company');
              $table-&gt;string('status')-&gt;default("available");
              $table-&gt;timestampsTz();
  
          });
      }
  
      /**
       * Reverse the migrations.
       *
       * @return void
       */
      public function down()
      {
          Schema::dropIfExists('vehicles');
      }
  }
  </code></pre>
  
  <p>I want to give nullable values to these columns.
  1.service_date
  2.service_freq_km
  3.service_freq_months</p>
  
  <p>How can I alter these columns as nullable in mysql?</p>