在现有的表中添加列时出错

我正在使用laravel 5.3，想在现有表（即course_chapters）中添加列。因此，我通过命令创建了迁移文件。

 php artisan make:migration add_description_to_course_chapters_table --table=course_chapters

迁移文件已被创建，我已添加了一些代码以在该表中添加列，如下：

<?php use Illuminate\Support\Facades\Schema; use Illuminate\Database\Schema\Blueprint; use Illuminate\Database\Migrations\Migration; class AddDescriptionToCourseChaptersTable extends Migration { public function up() { Schema::table('course_chapters', function (Blueprint $table) { $table->text('description')->after('title');
           });
       }
       public function down(){
           Schema::table('course_chapters', function (Blueprint $table) {
               $table->dropColumn('description');
           });
       }
   }

然后我运行命令 php artisan migrate，但表没有被创建，取而代之的是我得到了错误。

←[37;41m
   ←[39;49m
←[37;41m  [Illuminate\Database\QueryException]
   ←[39;49m
←[37;41m  SQLSTATE[42000]: Syntax error or access violation: 1064 You have  an error i  ←[39;49m
←[37;41m  n your SQL syntax; check the manual that corresponds to your MariaDB server  ←[39;49m
←[37;41m   version for the right syntax to use near ') default character set    utf 8 col  ←[39;49m
←[37;41m  late utf8_unicode_ci' at line 1 (SQL: create table     `course_chapters` () def  ←[39;49m
←[37;41m  ault character set utf8 collate utf8_unicode_ci)
   ←[39;49m
←[37;41m
   ←[39;49m
←[37;41m
   ←[39;49m
←[37;41m  [Doctrine\DBAL\Driver\PDOException]
   ←[39;49m
←[37;41m  SQLSTATE[42000]: Syntax error or access violation: 1064 You have   an error i  ←[39;49m
←[37;41m  n your SQL syntax; check the manual that corresponds to your   MariaDB server  ←[39;49m
←[37;41m   version for the right syntax to use near ') default character set   utf 8 col  ←[39;49m
←[37;41m  late utf8_unicode_ci' at line 1
←[37;41m
   ←[39;49m
←[37;41m  [PDOException]
   ←[39;49m
←[37;41m  SQLSTATE[42000]: Syntax error or access violation: 1064 You have   an error i  ←[39;49m
←[37;41m  n your SQL syntax; check the manual that corresponds to your     MariaDB server  ←[39;49m
←[37;41m   version for the right syntax to use near ') default character set    utf 8 col  ←[39;49m
←[37;41m  late utf8_unicode_ci' at line 1
   ←[39;49m
←[37;41m
   ←[39;49m

有什么解决办法吗？我的现有表的迁移文件是

<?php use Illuminate\Support\Facades\Schema; use Illuminate\Database\Schema\Blueprint; use Illuminate\Database\Migrations\Migration; class CourseChapters extends Migration { /** * Run the migrations. * * @return void */ public function up() { Schema::create('course_chapters', function (Blueprint $table) { $table->increments('id');
           $table->integer('course_id');
           $table->integer('chapter_id');
           $table->string('title', 80);
           $table->string('source');
           $table->string('source_type');
           $table->string('max_attempts');
           $table->tinyInteger('status');
           $table->timestamps();
       });
    }
   /**
    * Reverse the migrations.
    *
    * @return void
    */
    public function down()
    {
        Schema::drop('course_chapters');
    }
 }