This will be pretty hard to answer definitively without having a lot more information about all the tables and fields in the database.

Totally grasping at straws, I'm wondering if the table that has the company names also has a CompanyId field and if so then maybe the CompanyId field is related the RevenueId field in the other table.

One possible way to see relationships is to add the table with the company names to a new database diagram in SSMS and then right-click in the new diagram window and pick "Add Table..." to add the table with the company names to the diagram. Once the table comes up in the new diagram window you can right-click the table and pick "Add Related Tables". That option will be greyed-out (disabled) if the table has no related tables. If the option is enabled and you click it, all the related tables will be added to the diagram. You can then check the properties of each relationship to see what columns in the other tables are related to what columns in the table with the company names.