Global PHP "sort through" vs other fields In drupal views, you can create a field called "global php" and insert your own php code. Also as well, it has a sort feature which is handy when your view style is a table. 

However, the other fields does not have a "sort" feature on them. Is there a way to add it to them? Or does it just have to come with it, like global php does?
It has to be supported by the module supplying the field. In hook_views_data(), each defined field has a 'sort' element that defines the sort handler function for the field.