How to change the value of a row in views
You could try using Views Conditional


  Views Conditional is a simple module that allows you to define
  conditionals (if xxx then yyy) with fields in views. Conditions
  include:
  
  
  Equal To
  Not Equal To
  Greater Than
  Less Than
  Empty
  Not Empty
  
  
  Views conditional allows you to output text based on the result of the
  condition.


As per the readme.txt


  How to use Views Conditional:
  
  
  Create a view. Add some fields under "FIELDS".
  Click on "ADD" next to fields. Scroll down to "Views: Views Conditional", probably found near the bottom of the list.
  Add and configure fields...
  Choose a field to run a condition against, and provide values accordingly.
  Save, views conditional handles the logic and returns as specified.