Value Set Customization

Summary:

We need a list of values for a Purchase Requisition DFF field. LOV will pick from items table so we will create a table based value set. However, we would like to filter the table SQL based on the Business Unit (BU) of the Requisition.

Please advise if any of the following options are feasible in general:

1. Read the value of a field from the page where the DFF is shown.
2. Read the user id(Login id) of the user who is working on the requisition. We can then use the query to fetch the User's BU.
3. How we can select distinct values in value set query or use group by.