ER Diagram for Workflow

[Martin Obongita]

Hi All,
This is a Postgresql question.
Could anyone please give a hint on how I could create a table to track:
1. Changes to fields
2. Approve changes to fields
3. List of approvers and their level of approval
4. Status of changes (Open, Pending, Approved, Rejected)
ETC
In Studio 10.2 I would like to incorporate alerts and notifications of the workflows.
My biggest challenge is how to reference the approval requests and the records.
As always, your helps are appreciated very much.

Martin Obongita.