Using Drupal 7 Rules, how to react to a file upload and change a node field? I have spent hours/days trying to figure out how to accomplish this in Drupal 7 using the Rules module, so I will greatly appreciate any help anyone can provide.

What I am trying to do:

When a user re-uploads a file to a node, the node should rollback from an Approved status to Pending Review. This requires some kind of automated rule that checks for when a file was updated.

Here's what I have:


A node called Data_set with a File field called data_set_file.
Data_set nodes also have a field called Status (e.g., Pending Review, Approved).


My problem:

When a user uploads and overwrites an existing attachment in the data_set_file field, I want the node's Status to change back from Approved (if already) to Pending Review. I am able to use Rules to check for when a user uploads a new file, but there are no rules conditions to check for which file or node file has been updated. 

What I tried:

I created a "NOT Data Comparison" condition between node-unchanged:field-dataset-file:file:fid and (Equals/Negate) node:field-dataset-file:file:fid However, when updating the file, it did not register a change to the fid field (because it keeps the same fid). I also tried the file size field with no effect as well. When I tried the file's timestamp, it appeared to work at first until I realized that the timestamp updates every time, no matter what, that a user saves a node, regardless of whether or not a file was re-uploaded.

I may be going about this the wrong way. Anyone know what's the easiest way to accomplish this? Thanks a million!
Workflow 


  This module allows you to create arbitrary Workflows, and assign them
  to Entities.
  
  Workflows are made up of workflow states. Transitions between states
  can be allowed per role. For example, a workflow with the states
  Draft, Review, and Published could be assigned to the Story node type.
  Only users with role 'chief editor' can set Stories to the published
  state. You can set up the Workflow to alter states from form, page,
  comment and a special workflow tab.
  
  Transitions between workflow states can have actions assigned to them.
  In our example, we could assign an action so that when the story moves
  from the Draft state to the Review state an email is sent out. Another
  action could be assigned to the transition from Review to Published so
  that the node's status is set to Published (and becomes visible on
  your website).


How we use workflow module 

Creating a Workflow

Editorial workflow with Rules