At KnackForge we often see requirement to expose custom fields to views for better integration with Drupal flow. In this article we are going to see steps to expose a custom field from a custom table. Infact its a virtual field.
Assume you have two custom fields total_marks and marks_obtained in a custom table. Now you need to calculate the percentage of mark scored. You don't need a field in table for this. You can create a virtual field bound to marks_obtained field.