title: Add custom field during select mysql in laravel query
body: <p>I have this query in laravel 5.2</p>
  
  <pre><code>$obj_custom_stdy_data = QstCustomStudyData::where('student_id', $this-&gt;data_user['student_id'])
                      -&gt;select($list_id . ' as list_id ', 'chapter_id', 'subject_id', 'subject_code_id')
                      -&gt;get()
                      -&gt;toArray();
  </code></pre>
  
  <p>Well I have a fixed value <code>$list_id</code> got from top code. Actually I want to add new field during query selection as <code>list_id</code>. However I got error for such that method.</p>
  
  <p>When I tried in mysql IDE for example:</p>
  
  <pre><code>SELECT (1+2) as total, c.* FROM users
  </code></pre>
  
  <p>Then the result is no wrong at all.</p>
  
  <p>Is that anyway to write in query builder for laravel instead of <code>raw</code> style?</p>